(2х-7)(х+1)+3(4х-1)(4х+1)=2(5х-2)²-53

2x²+2x-7x-7+3(16x²-1)=2(25x²-20x+4)-53

2x²+2x-7x-7+48x²-3=50x²-40x+8-53

50x²-5x-10=50x²-40x-45

-5x-10=-40x-45

-5x+40x=-45+10

35x=-35

x=-1

Ответ: -1

(2x-7)(x+1)+3(4x-1)(4x+1)=2(5x-2)²-53

2x²-7+2x-7x+48x²-3=50x²-40x+8-53

35x=-35

x=-1