Question

Which of the following is the equation of a line perpendicular to the line y = -10x + 1, passing through the point (5,7)?

Answer 1

Line 1;
y=-10x+1
Gradient m= -10
Gradient of line 2= 1/10
$\frac{y-5}{x-7} = \frac{1}{10}$
y-5=$\frac{1}{10} {x-7}$
y-5=$\frac{1}{10} x- \frac{7}{10}$
y=$\frac{1}{10} x- \frac{43}{10}$

Answer 2

The answer is C. This is because when you solve you get y=1/10x+6.5 this graph runs through the point (5,7) and is perpendicular to y=-10x+1. In order for two equations to be perpendicular their slopes will be the opposite.