## Calculus (3rd Edition)

Equation of a line in point-slope form is $y-y_{1}=m(x-x_{1})$ Given: m=2, $x_{1}=1$ and $y_{1}=4$ Therefore, equation of the line is $y-4=2(x-1)$ or $y=2x+2$. When x=3, $y=2\times3+2=8$