1 . 与几何证明一样,代数推理也需要有理有据.请先完成第(1)题的填空,再完成第(2)题的证明.
(1)已知实数x,y满足
,求证
.
证明:∵
,
∴
(实数的加法法则),
(不等式的基本性质1).
∴
(①).
∵
(②),
∴
.
∴
(③).
(2)已知实数x,y满足
,求证
.(注:无需写出每步的依据.)
(1)已知实数x,y满足
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6d229cbec798c9c278a9b5979cb38247.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ba8073266cfa99b04190473d16b615a8.png)
证明:∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6d229cbec798c9c278a9b5979cb38247.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c6fa0bb61ce60310f18cb95bf2e83c8a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bdb9873dfaf15e799fa6fb0128433725.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be487f86d23ca6027e19c8fccc5aa992.png)
∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c61f51f0956345e4381e4a86982c551.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/43db43c7452258a0d37f8b9ee9c69180.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ba8073266cfa99b04190473d16b615a8.png)
(2)已知实数x,y满足
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6d229cbec798c9c278a9b5979cb38247.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d168aaaa03c5eeff1b2ebdd688346af6.png)
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2024八年级下·江苏·专题练习
2 . 在
中,
,以斜边
为边向
形外作正方形
,若正方形
的对角线交于点
(如图1)
平分
.
(2)试猜想线段
与
,
之间的数量关系,请写出结论并证明.
(3)过点
作
于
,过点
作
于
,
和
的反向延长线交于点
(如图2),求证:四边形
为正方形.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0cec4464b5efa55e9b33a677d983667e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1070d38d2fea1dc88c6eb31d320b763.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0cec4464b5efa55e9b33a677d983667e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f90c780dac29ff8b7df5881d3b33abab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1a55a1a244f81097e05e715b69580faa.png)
(2)试猜想线段
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a299d2b999568e80be8005565ba209a4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ccaee8f228ff24e7c89879bb5b999cf2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1642eec556eb252de9c1ab7bb5ca90b3.png)
(3)过点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3645abd3cf4383639817c8eb6b21a623.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/70cbb84986a7645bc3acb2b3d01fc106.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73465a1f9aa03481295bf6bd3c6903ac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4cae70b8a9d2d2e96dea62c00ced04b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c7e4fa04825ac7d071968056322d88be.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/895dc3dc3a6606ff487a4c4863e18509.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/611f100dcfa7803db6eb233e2e7f2dab.png)
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3 .
中,
分别为
的中点,
为
的中点,
的延长线交于点
.
;
(2)猜想线段
与线段
的数量关系,并证明你的结论.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d3a51949f48ee8cf746851ba779b078e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0d54431bbb28ebd98db5c1dc6083a75.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1fc56c77464a17a1e97b568762a3e2c6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/97c6c0b5660ccb8d8f909dd17e2f8bc7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/895dc3dc3a6606ff487a4c4863e18509.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e94f3fde8f3a147bae1d14b5ef590468.png)
(2)猜想线段
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/abf80148409afb32ced0b4f59f1ba709.png)
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4 . 如图,在等边
中,D是边
上的一点,点E在边
的延长线上.
.(请从信息“①
,②D为
的中点,③
”中选择两个分别填入两条横线中,将题目补充完整,并完成证明.)
(2)过点D作
于点M,在(1)的条件下,当
,求
的长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5eaffcd2070bfcb1955e2cab66c26c06.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dca4fa129b5352b0bf5542965098ea0c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6bf5abeea8aef4f9168fce6380c899f3.png)
(2)过点D作
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/07789d6a8259ac89144caa816aaaf47d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d75103aaf28272c6172b2aee3abd41f0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
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5 . 完成下面的证明:
如图,
,垂足分别为
,且
.求证:
.
(已知)
,
(垂直的定义),
.
(同位角相等,两直线平行).
( )
又
(已知),
.
( )
如图,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5fbd879713785f77d6d40527b26b9d36.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8eede2212c3f3fb34c2c144cd1948879.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/823e59e9ec3c246cb2c20d61cdfa3a28.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca14fa885a9d04f04e0418b49b118241.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54df0a725d5fba7ccb62902c3294185b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54328b651a0a07825ce5ad20caf9bb34.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83873a9d782f2588c5eedbfe73f9bc2f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2ecc173b229b6de8ded9668aced26977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83873a9d782f2588c5eedbfe73f9bc2f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3f986ad7e0e7203512a0788625de13b0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/032ed5dce395e6b0d72a1734a7a616a8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/da3dcb3b4ad5ae8aace34bb0a93bceda.png)
又
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e224911647f98bcd452589f6b0f6f1a5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/debead9e8c5cb94a1313bc7d7e420b9c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7af324e97c931e72964c9fc8dbc3b7c8.png)
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6 . 用两种方法证明“三角形的内角和等于
”.
,
求证:
.
证法1:如图,过点A作
,
∵
,
∴
___(两直线平行,内错角相等),
(___),
即
,
∴
.
请把证法1补充完整,并用不同的方法完成证法2.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bfe639eab78eafd2d40ea70aa5d3f21d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/791e819abbe4ecc6f2e7209839c4fc0b.png)
证法1:如图,过点A作
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6dceb5cc71fc50f20649f6b9535fd914.png)
∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6dceb5cc71fc50f20649f6b9535fd914.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d8ae5d4889c664ac89681cb7463e119.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a774b508d6e5df94940125d3a53e20a8.png)
即
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5a0e1719c0a7c8649662366dcee2511.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1647157963cbc066cccf8f995d6a975e.png)
请把证法1补充完整,并用不同的方法完成证法2.
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名校
7 . 用反证法证明“已知
,
.求证:
.”第一步应先假设______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c6a46e678bf9d2df5ad4c782b3dc22f5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20d70009d48ea5ed5e20cc5eff3d557e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fc8e2b380189700530b3352b501c532d.png)
您最近一年使用:0次
2024-04-24更新
|
101次组卷
|
2卷引用:江苏省镇江市外国语学校2023-2024学年八年级下学期期中数学试题
8 . 【阅读理解】如图1,在矩形
中,若
,
,则
________(用含a、b的式子表示);
【探究发现】如图2,小华发现在平行四边形
中,若
,
,则上述结论依然成立,请你跟随小华的思路,帮他继续完成证明过程 .
证明:如图3,延长
,过点B、点C分别作
于点E,
于点F.
在
中,
且
,
,
.
.
设
,
.
……
________(请继续完成以上证明)
【拓展提升】如图4,已知
为
的一条中线,
,
,
.
求证:
.
【尝试应用】如图5,在矩形
中,若
,
,点P在边
上,则
的取值范围为________.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6d42e97eee705d164e6ac6de9ecd6d1f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a4a88b719166fcc1431f876bc8c5656c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acb11258c0ab2cfc4107bd261816e8dc.png)
【探究发现】如图2,小华发现在平行四边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6d42e97eee705d164e6ac6de9ecd6d1f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a4a88b719166fcc1431f876bc8c5656c.png)
证明:如图3,延长
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/67d822262ff00915910e5b87d81ad1ba.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c897a54f2e36bc4b52fba74b41c89d2d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0b62ce0cbffa4758c7a0e6fb7ca4d24e.png)
在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5138a9f70d5e8b0580e30fef6eb7baef.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c220eadc312101e2fb89dfe920f7b30d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b0fff774b4b0087a6f304ce930d359be.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5279bd0b34bff51b7fe30b9c90c5d7e1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/278fbac03b1927688e382c0031950ae4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f3411384689995f6c3ff4108d1ffcbad.png)
设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4a08c6e0e1a47f5e2c8cfd97782045bb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cded8269dc8e7be712b8cfe06e48b79c.png)
……
________(请继续完成以上证明)
【拓展提升】如图4,已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aaf1438142deeac876fc7dc50552e552.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6d42e97eee705d164e6ac6de9ecd6d1f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a4a88b719166fcc1431f876bc8c5656c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/da01f682d1d4e5dd24bd26ec18540b4b.png)
求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/99573c6dd1937689a0f699a46643d55f.png)
【尝试应用】如图5,在矩形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d2c15801fee2405573677484f5dcfa4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/07160f14b3b453bebb64cb2bf96dc85a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c690c09eded0306872d1bf42cb4c1d6c.png)
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9 . 在边长为4的正方形
中,
从点
向点
运动,点
从点
向点
运动,它们运动速度相同,当点
运动到点
时停止运动,点
也随之停止运动.
①求证:
;
②当点
运动到何处时,
?请加以证明.
(2)如图2,若点
从点
向点
运动,点
从点
向点
运动,它们运动速度相同,当点
达到点
时停止运动,点
也随之停止运动. 在整个运动过程中,
与
的交点为
,请求出
的最小值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
①求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a4e22ba3e6e1c1d6b12d9b8baa8d1f02.png)
②当点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0d86bdca15922c7896ffe4de3a06bc21.png)
(2)如图2,若点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6aa2b5e09f8ec785c59900a529390a02.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f41119955cc620e50b54e3579033fa0a.png)
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10 . 把下面的证明补充完整.
已知:如图,在四边形
中,
,
,
平分
,交
于点
,
平分
,交
于点
.求证:
.
平分
,
(______),
平分
,
,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3ed55f99888105994f59e177310bdf5a.png)
______(等量代换)
(已知),
(______),
______,
.
已知:如图,在四边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8a11029ca6b4b9e7f777af0280cf163c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d01fc460614df9db458986ae7de8327e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d004d2d115b477ade6af7ddb93db0df8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3981e7286d41960daf4e110c1c84e03a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d39b8d91afc34e4a9b0fdbb6bafb9087.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a2612c3ed33135b60b5a08c173c9f84.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5c369409d47f8c1fb12be8705fe7fa52.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3981e7286d41960daf4e110c1c84e03a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/87dd2b88b213ee49fa39934592cec7a5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f85f511236e5645290b9d06984558ea0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d39b8d91afc34e4a9b0fdbb6bafb9087.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bf5bc7c182042131e238f30145603f8f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3ed55f99888105994f59e177310bdf5a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2de0d10ef8b748d4531250c37c5d3f9e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60cc741b6fba7ce725bf7bb6270c8ba2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b5bde532c621d1a6ff365c19a0d49e4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2de0d10ef8b748d4531250c37c5d3f9e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb21a6feebc27941cfdef7f2dc845865.png)
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