已知y是x的一次函数,当x=2时,y=-1,且这个一次函数的图象与直线y=2x平行.试求y与x的函数关系式.
更新时间:2016-12-05 19:20:33
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【推荐1】如图,在平面直角坐标系中,
,
,过点
作直线
轴,点
是直线
上的动点,以
为边在
右上侧作等腰直角
,使
.
![](https://img.xkw.com/dksih/QBM/editorImg/2024/1/15/bd6429f9-7689-4458-a0f6-b68f82e19266.png?resizew=527)
(1)如图1当点
落在点
时,则点
的坐标是________;
学生甲认为点
的坐标一定跟点
有关,于是进行了如下探究:
(2)如图2,小聪同学画草图时,让点
落在
、
、
不同的特殊位置时(
在
轴上、
与
轴平行、当
落在
轴上时对应点
),画出了几个点对应的
、
、
三个不同的位置,发现
、
、
在同一条直线上,请你根据学生甲的猜测及题目条件,求出点
所在直线的解析式;
(3)在(2)中,虽然求出了点
所在直线的解析式,但是小明同学认为几个特殊点确定解析式是一种猜测,当点
在
上运动时,所有的
点都在一条直线上吗?就解设了点
的坐标为
,希望用一般推理的方式求出
和
满足的关系式,请你帮助小明给出解答.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/40630a669f4eedf626bc24851df10c85.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76d03fa28c117649b0fdfe17eed7b583.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/25795c2dc456965454bdc16fd9c06e91.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f85fca60a11e1af2bf50138d0e3fe62.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20a541b81584a032f571159ea152c85a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20a541b81584a032f571159ea152c85a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d9763846b1131e1e3e2d741ad95d5bb0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a45f435b604c73af7053422243b66cd5.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/1/15/bd6429f9-7689-4458-a0f6-b68f82e19266.png?resizew=527)
(1)如图1当点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
学生甲认为点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
(2)如图2,小聪同学画草图时,让点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2708fa6298e52f617383efc175b71ddc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b9cb8e6ff801523b0304576cd69fd2d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/797e67927616b141ed7c6b83f8b6f4fb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2708fa6298e52f617383efc175b71ddc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d3de68627f7f3d7f81b61bf743f311ea.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/797e67927616b141ed7c6b83f8b6f4fb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a86380a6d6501f6504dcb4aa5e3099f2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eae863e7a1f1fed09f1075de4a817c63.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5f52b152eaf63415b10ed786a58a2747.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a86380a6d6501f6504dcb4aa5e3099f2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eae863e7a1f1fed09f1075de4a817c63.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5f52b152eaf63415b10ed786a58a2747.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
(3)在(2)中,虽然求出了点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f85fca60a11e1af2bf50138d0e3fe62.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0203b006524305c3d8ee0b6c34cd872b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
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【推荐2】已知一次函数y=(m+3)x+m﹣4,y随x的增大而增大.
(1)求m的取值范围;
(2)如果这个一次函数又是正比例函数,求m的值.
(1)求m的取值范围;
(2)如果这个一次函数又是正比例函数,求m的值.
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真题
【推荐1】在直角坐标系中,直线y
x与反比例函数y
的图象在第一、三象限分别交于A、B两点,已知B点的纵坐标是﹣2.
![](https://img.xkw.com/dksih/QBM/2021/12/16/2873946641514496/2875187050766336/STEM/1b2353d89b854adeba4d4adc2686961b.png?resizew=273)
(1)写出点A的坐标,并求反比例函数的表达式;
(2)将直线y
x沿y轴向上平移5个单位后得到直线l,l与反比例函数图象在第一象限内交于点C,与y轴交于点D.
(ⅰ)S△ABC S△ABD;(请用“<”或“=”或“>”填空)
(ⅱ)求△ABC的面积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/514236164053e00a44b3e9b462ef687d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/860c93fe10745d9539006b34f374ccfd.png)
![](https://img.xkw.com/dksih/QBM/2021/12/16/2873946641514496/2875187050766336/STEM/1b2353d89b854adeba4d4adc2686961b.png?resizew=273)
(1)写出点A的坐标,并求反比例函数的表达式;
(2)将直线y
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/514236164053e00a44b3e9b462ef687d.png)
(ⅰ)S△ABC S△ABD;(请用“<”或“=”或“>”填空)
(ⅱ)求△ABC的面积.
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【推荐2】阅读下面的材料:
在平面几何中,我们学过两条直线平行的定义.下面就两个一次函数的图象所确定的两条直线,给出它们平行的定义:设一次函数
的图象为直线
,一次函数
的图象为直线
,若
,且
,我们就称直线
与直线
互相平行.已知一次函数
的图象为直线l,过点
且与已知直线l平行的直线为
.解答下面的问题:
![](https://img.xkw.com/dksih/QBM/editorImg/2023/4/28/d339ff4d-4dfe-41da-8068-90f3ae8e35d2.png?resizew=202)
(1)直接写出直线
的函数表达式;
(2)设直线
分别与
轴、
轴交于点
,
,过坐标原点
作
,垂足为点
,求
和
两平行线之间的距离
的长;
(3)若
为
上一动点,求
的最小值,并求取得最小值时点
的坐标;
(4)在
轴上找一点
,使
为以
为腰的等腰三角形,请直接写出点
的坐标.
在平面几何中,我们学过两条直线平行的定义.下面就两个一次函数的图象所确定的两条直线,给出它们平行的定义:设一次函数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a1ef2acd20641f029f4a102f240b863.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2e9b0f5f44abbc6544a2f672b025b013.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d537af52b7a7ae24b3cb67a2725b05c2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3f6f17bc385bafb37e8f964e5eb99cd0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c53ea3373af8c2c835a1bfbe2c742d8a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/222f64d83170dc4dbab1e9cfb6924720.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2e9b0f5f44abbc6544a2f672b025b013.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3f6f17bc385bafb37e8f964e5eb99cd0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4407788e4dc88210bca71a2551d4f2f9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/915651fc9cdae8de0bf6fddbaad641d8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/4/28/d339ff4d-4dfe-41da-8068-90f3ae8e35d2.png?resizew=202)
(1)直接写出直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
(2)设直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/771b610e4ddefa739a985d1e5462ce5a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f85fca60a11e1af2bf50138d0e3fe62.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/828628c0876b45381c9a0edeb0fec236.png)
(3)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef4113c492885ba7c47fe42ac792578f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2f1216d88992d966f21673c7c3022a07.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
(4)在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6074f4beb31fb393ae3978e0035ae16f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2be49c37e30a3ced0364c3e74d8c687.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
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解题方法
【推荐3】阅读下面材料:
我们知道一次函数y=kx+b(k≠0,k、b是常数)的图象是一条直线,到高中学习时,直线通常写成Ax+By+C=0(A≠0,A、B、C是常数)的形式,点P(x0,y0)到直线Ax+By+C=0的距离可用公式d=
计算.
例如:求点P(3,4)到直线y=﹣2x+5的距离.
解:∵y=﹣2x+5
∴2x+y﹣5=0,其中A=2,B=1,C=﹣5
∴点P(3,4)到直线y=﹣2x+5的距离为: d=
=
=
=![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2967337e3fcb228dded64ab0c41a17e0.png)
根据以上材料解答下列问题:
![](https://img.xkw.com/dksih/QBM/2022/3/1/2927095188848640/2927707650932736/STEM/50dd2347-6f5d-4ebe-8fc8-20b87ca7a0bd.png?resizew=160)
(1)求点Q(﹣2,2)到直线3x﹣y+7=0的距离;
(2)如图,直线
=﹣x沿y轴向上平移2个单位得到另一条直线
,求这两条平行直线之间的距离.
(3)若将
绕其与y轴的交点逆时针旋转90度与
相交,直接写出
大于
时,x的取值范围
我们知道一次函数y=kx+b(k≠0,k、b是常数)的图象是一条直线,到高中学习时,直线通常写成Ax+By+C=0(A≠0,A、B、C是常数)的形式,点P(x0,y0)到直线Ax+By+C=0的距离可用公式d=
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/18b2961beea1ca9a5a0a71ae86005fce.png)
例如:求点P(3,4)到直线y=﹣2x+5的距离.
解:∵y=﹣2x+5
∴2x+y﹣5=0,其中A=2,B=1,C=﹣5
∴点P(3,4)到直线y=﹣2x+5的距离为: d=
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/18b2961beea1ca9a5a0a71ae86005fce.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3ec2d78c8feeec7e8c5ae37587144d7b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/19ce176879abaa2b45959f0ed93b5022.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2967337e3fcb228dded64ab0c41a17e0.png)
根据以上材料解答下列问题:
![](https://img.xkw.com/dksih/QBM/2022/3/1/2927095188848640/2927707650932736/STEM/50dd2347-6f5d-4ebe-8fc8-20b87ca7a0bd.png?resizew=160)
(1)求点Q(﹣2,2)到直线3x﹣y+7=0的距离;
(2)如图,直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f16106c3fcda32215473eb9c6da99d12.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3f6f17bc385bafb37e8f964e5eb99cd0.png)
(3)若将
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3f6f17bc385bafb37e8f964e5eb99cd0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2e9b0f5f44abbc6544a2f672b025b013.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2e9b0f5f44abbc6544a2f672b025b013.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3f6f17bc385bafb37e8f964e5eb99cd0.png)
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