( х+7)(5х-4)-(х+7)(4х-3)=0
(5x^2-4x+35x-28)-(4x^2-3x+28x-21)=0
x^2+6x-49=0
D=36-4•(-49)=232
x=-6±√232/2
( х + 7)( 5х - 4) - ( х + 7)( 4х - 3)=0
( х + 7) 5х - 4 - х - 7 (4х - 3) = 0
5х²+ 35х - 4 - х - 28х - 21 = 0
5х²+ 35х - х - 28х= 0+ 4 +21
31х = 25
х= 0,806
