find the value of a so that the points A(6, 2a) and B(a, -2) lie on a line having slope 7.
Well, think about it! A slope of seven means that the \(\frac{\text{change in y}}{\text{change in x}}=7\). So, using our formula, we can make an equation from your points, giving\(\frac{2a-(-2)}{6-a}=\frac{2a+2}{6-a}=7 \). See if you can solve the equation for yourself now!