(2-5х)"2=9 Решите плиз!)

Question

(2-5х)"2=9 Решите плиз!)

Answer 1

(2-5х)²=9
4-20х+25х²-9=0
25х²-20х-5=0
5х²-4х-1=0
D=b²-4ac=16+20=36
x1=-b+√D/2a=4+6/10=10/10=1
x2=-b-√D/2a=4-6/10=-2/10=-0.2