Question 870278
5x^2 =8x+21

5x^2 -8x-21=0

5x^2-15x+7x-21=0

5x(x-3)+7(x-3)=0

(x-3)(5x+7)=0
x=3 OR x=-7/5

5*3^2=45
8*3+21=45