Question

In the xy-plane, line n passes through point (0,0) and has a slope of 4. If line n also passes through point (3,a), what is the value of a?

Answer 1

`\begin{gathered} (y_2-y_1)=m(x_2-x_1) \\ _{} \\ (y_2-0_{})=4(x_2-0) \\ y_2=4x_2 \\ \text{when x}_2=3 \\ y_2=12 \\ \text{Therefore, a}=12 \\ \\ \\ _{} \\ \end{gathered}`