Question

What is the value of y so that the line through (3, y) and (2, 7) is parallel to the line through (-1, 4) and (0, 6) ?

Answer 1

$\text{Slope of line joining (-1, 4) and (0, 6) is}{m}_1=\frac{6-4}{0-(-1)}=2\text{Slope of line joining (3, y) and (2, 7) is}{m}_2=\frac{7-y}{2-3}=y-7\text{Since the two lines are parallel}{m}_1=m_2\Rightarrow 2=y-7\Rightarrow y=9$