How to do (5x + 7) (2x-3) - (10x + 1) (X-2)?

How to do (5x + 7) (2x-3) - (10x + 1) (X-2)?

（5x+7）（2x-3）-（10x+1）（x-2）
=10x²-x-21-(10x²-19x-2)
=10x²-x-21-10x²+19x+2
=18x-19

If x ^ 2 + 2x-1 = 0, then 5x ^ 2 + 10x-3

x^2+2x-1=0,x^2+2x=1
5x^2+10x-3=5(x^2+2x)-3=5*1-3=2

The square of x-5x-176 = 0, x =?

X-5x-176 = 0 by cross multiplication: (X-11) (x + 16) = 0, we get x = 11 or x = - 16

Given a = x ^ 2-5x, B = x ^ 2-10x + 5, find the value of 2a-b when x = - 2 / 1

Is it x = - 1 / 2?
2A-B
=2(x^2-5x)-(x^2-10x+5）
=2x^2-10x-x^2+10x-5
=x^2-5
If x = - 1 / 2
The original formula = (- 1 / 2) & # - 5 = 1 / 4-5 = - 4 and 3 / 4
If x = - 2 out of 1 = - 2
The original formula = (- 2) & # 178; - 5 = 4-5 = - 1