Question

The slope of line m is 7/8. If n⊥m, what is the slope of line n?

Answer 1

$k:y=m_1x+b\\l:y=m_2x+c\\\\l\ \perp\ k\iff m_1m_2=-1$
We have:
$m_1=\dfrac{7}{8};\ m_2=?$
Substitute:
$\dfrac{7}{8}m_2=-1\ \ \ \ |\cdot\dfrac{8}{7}\\\\m_2=-\dfrac{8}{7}$
Answer: D)

Answer 2

Hey there !

When two lines are perpendicular , the product of their slope is -1 ,

m1 × m2 = -1
7/8 × m2 = -1

m2 = -8/7 Ans.