1 . 已知数列
满足
.
(1)求
,
,
的值,猜想并证明
的单调性;
(2)请用反证法证明数列
中任意三项都不能构成等差数列.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b28ef6f1b2279af482557a8ea46f2e43.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5a89184cc08d4b405a584393c6065d4e.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8d04a8b7a7595251251b8e0b7e665e8c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a5453ec6a9e8b96357c888ea863ddcf7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5c85bd8a6ac6110719b0cb7f1a78b3a6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b28ef6f1b2279af482557a8ea46f2e43.png)
(2)请用反证法证明数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b28ef6f1b2279af482557a8ea46f2e43.png)
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2 . 已知
,试用反证法证明
中至少有一个不小于1.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/30212ea3f694a0591c925c1f899acc71.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76f0649064a085fb74c997fb507a9b6d.png)
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3 . 请解决下列问题:
(1)已知
,证明:
.
(2)用反证法证明:三个数
中,至少有一个大于或等于
.
(1)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/07c47599e2a10a7a6747a6d15e12b34b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f8f3bf714dcba0fcc8483f0fa0f3d64f.png)
(2)用反证法证明:三个数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2e6a8e3f3ac3af2452dad7ad1e37a4f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0cf3f23bfec394769b4670962b219999.png)
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4 . 已知函数![](https://staticzujuan.xkw.com/quesimg/Upload/formula/feee682fd931af41b6e77ee0754a53d3.png)
(1)若t>0,用分析法证明∶
;
(2)若a>0,b>0,a+b>2,求证∶af(b)与bf(a)中至少有一个大于
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/feee682fd931af41b6e77ee0754a53d3.png)
(1)若t>0,用分析法证明∶
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d7f41afed997d68ebd02d4d296228e3e.png)
(2)若a>0,b>0,a+b>2,求证∶af(b)与bf(a)中至少有一个大于
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4dac452fbb5ef6dd653e7fbbef639484.png)
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5 . 在△ABC中,角A,B,C的对边分别为a,b,c,已知a,b,c互不相等,且
.
(1)试比较
与
的大小;
(2)求证:B不可能是钝角.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2cd5a7ec932f12eacb2e8793af166d33.png)
(1)试比较
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61fe34b1cc3a3cfcfad66fb03b9e22c1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c147d6cbd7cbaeb8ec08a0ba69cd59dd.png)
(2)求证:B不可能是钝角.
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6 . (1)用分析法证明:
;
(2)用反证法证明:
为偶数.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3561ca61b40d4aa2d9707e2f52e2fd57.png)
(2)用反证法证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/86304331bada90a177e771aec10da689.png)
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名校
解题方法
7 . (1)已知复数
满足
,求
.
(2)若
均为实数,且
,求证:
中至少有一个大于0.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e81e59019989b7dc2fb59b037ef6e010.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fa36cb9fccbf0536ee36032d9031da2c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/de971553ea8a66d7849b138a4a0625c5.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1a14c388e1e2e5a2ff1ccf6caffbee0d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca815cf1fab1f90faae2c21f91be6d86.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1a14c388e1e2e5a2ff1ccf6caffbee0d.png)
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8 . (1)用综合法证明:
,
,
均为正实数);
(2)已知:
,
,
,求证:
,
中至少有一个不小于
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54cfb2a3446d8011b89d87fba03a20e4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c94bb12cee76221e13f9ef955b0aab1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/071a7e733d466949ac935b4b8ee8d183.png)
(2)已知:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eb63478132d4c1fef3c17e591919da83.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/25d6b6b86228a9b721d618fae2963e57.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bd86a39ae4fb080287cda63e4a68266.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c94bb12cee76221e13f9ef955b0aab1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c95b6be4554f03bf496092f1acdfbb89.png)
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9 . 已知:
,
是正实数.求证:
与
不可能相等.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/16f0b84ee4ed90face0993d4f4dda379.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2696d72704a8274a995063527e89d38f.png)
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10 . 试写出直线与平面平行的判定定理并证明.(证明过程包括已知、求证和证明)
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