Question

(2x-1)(2x+1)-4(x+5)2=19

Answer 1

4х²+2х-2х-1-4(х²+10х+25)=19
4х²-1-4х²-40х-100=19
-40х=120
-х=3
х=-3

Answer 2

(a-b)(a+b)=a²-b²
(a+b)²=a²+2ab+b²

(2x-1)(2x+1)-4(x+5)²=19
4x²-1-4(x²+10x+25)=19
4x²-1-4x²-40x-100=19
4x²-4x²-40x=19+100+1
-40x=120
x=120/(-40)
x= -3