令Y=0,求出X,求纵截距就令X=0,求出Y。
如y=x-1横截距为1,纵截距为-1。直线截距可正,可负,可为0。
截距一般是用在直线上,是指直线与y轴交点的纵坐标,截距是一个数,是有正负的,直线方程y=kx+b中,b就是截距。
一般说截距就是指纵截距,横截距就是指直线与x轴交点的横坐标。这个概念也可以推广到一般的曲线。
![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/caef76094b36acaf6083b91072d98d1000e99cfe?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)
扩展资料
截距式方程:
已知直线l交于两点A(a,0),B(0,b)
先设直线l方程为:y=kx+m
代入A,B的坐标得
,
![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/d000baa1cd11728bd966a3cec6fcc3cec2fd2c96?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)
再把k,m的值代入方程y=kx+m
得:
![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/cf1b9d16fdfaaf519b6aae53825494eef11f7a54?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)
最后变形为截距式方程:
![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/a6efce1b9d16fdfac8e5e902ba8f8c5495ee7b54?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)