Question

what is the slope intercept form of the linear equation with a graph that passes through (-2,2) and is perpendicular to the graph of y=1/3x+9

Answer 1

$\text{The slope-intercept form}\ y=mx+b.\\\\Let\\k:y=m_1x+b_1\\l:y=m_2x+b_2\\\\l\ \perp\ k\iff m_1m_2=-1\\------------------------\\\text{Let}\ k:y=\dfrac{1}{3}x+9\ \text{and}\ l:y=mx+b\\\\l\ \perp\ k\iff\dfrac{1}{3}m=-1\qquad|\cdot3\to m=-3\\\\l:y=-3x+b\\\\\text{Substitute the coordinates of the point (-2, 2) to the equation}\\\text{of the line}\ l:\\\\2=-3(-2)+b\\2=6+b\qquad|-6\\-4=b\to b=-4\\\\\boxed{Answer:\ y=-3x-4}$