a easy question needed your confirm

steven.wei

直线y=5x垂直的直线为： y=1/5x, x=1/5y, y= (-1/5)x 等
【确认】y=1/5x
【思路】垂直,斜率相乘等于

the product of the slope of two 垂直的直线 should be -1, right?

needed confirm

陈月麟

yes, you are right.
If one slope is 2, then the slope of 垂直的直线 must be -1/2. Their product is -1. Pls tell me why answer is y = 1/5x. I think it should be -1/5x. Do u agree?