5a(a+1)=(3a-2)² помогите плз... Заране спс)

5a(a+1)=(3a-2)²
5a²+5a=9a²-12a+4
5a²-9a²+5a+12a-4=0
-4a²-17a-4=0
4a²+17a+4=0
D=17²-4*4*4=289-64= 225=15²
$a_{1}= \frac{-17- \sqrt{225} }{2*4} = \frac{-17-15 }{8} = \frac{-32}{8} =-4 \\ a_{2}= \frac{-17+ \sqrt{225} }{2*4} = \frac{-17+15 }{8} = \frac{-2}{8} =- \frac{1}{4}$