Apply C and D after this \frac{\alpha_1+\alpha_2}{\alpha_1-\alpha_2}=\frac{\beta_1+\beta_2}{\beta_1-\beta_2}
putting values and some reaagarnagemnts u get \frac{b^2-4ac^2}{b^2}=\frac{q^2-4pr}{q^2}
"*4ac above"
=> 1- \frac{4ac}{b^2}=1-\frac{4pr}{q^2}=>4ac/b^2=4pr/q^2=>ac/pr=b^2/q^2
=> GP