一道英文数学题

题目

一道英文数学题
write an equation for the line that is perpendicular to the given line and that pass thought the given point:
y=(-1/3)x+2 ;the point is (4,2)
(-10)x+(8)y=3; the point is (15,12)
列如:
y= 5x +3; the point is (0,2)
y =(-1/5)x-2
我想知道是怎么解的,

答案

y=(-1/3)x+2 ;the point is (4,2)求一条直线垂直于y=(-1/3)x+2,且过点(4,2)：所以所求直线为y=kx+b斜率k=-1/(-1/3)=3所以y=3x+b,把点(4,2)代入,解b=-10所以y=3x-102、(-10)x+(8)y=3化为y=5x/4+3/8所以所求直线为y=kx...