Question

8)What is the equation of a line that goes through the point (3, 12) and is perpendicular to the line given by the equation y = -1/3x - 7?

(A) y = -3x - 12
(B )y = -1/3x + 6
(C) y = 3x + 3
(D) = (1/3x) - 6

Answer 1

The slope of the first line is $m_1=\frac{-1}{3}$.
To be perpendicular the slope of the second line must be the negative reciprocal of the first: $m_2=3$
Use the slope-intercept formula: 
$y=mx+b$
Substitute known values:
$12=3(3)+b$
Solve for $b$:
$b=3$
Complete the formula:
$y=3x+3$