Find an equation of the line L, where L is perpendicular to y=3x and passes through the point (1,3)

Question

Please help me

Answer 1

Given points say(x1,y1) = (1,3)

Given line y = 3x

Slope of the line = 3

L is perpendicular to given line.

So slope of the L = -1/3.

line equation to L is y-3 = -1/3(x-1)

Cross multiplication.

3(y-3) = -x+1

3y-9 = -x+1

Add to each side by 9.

3y-9+9 = -x+1+9

3y = -x+10

Divide to each side by 3.

3y/3 = -x/3+10/3

So the line L is y = -x/3+10/3.