Question

Rút gọn biểu thức:

a, ( x+1 )^2 - ( x-1 )^2 - 3 . ( x + 1 ) . ( x - 1)

b, 5 . ( x + 2 ) . ( x - 2 ) - 1/2 . ( 6 - 8x ) + 17

HELP ME

 

Answer 1

a) \(\left(x+1\right)^2-\left(x-1\right)^2-3\left(x+1\right)\left(x-1\right)\)

\(=x^2+2x+1-\left(x^2-2x+1\right)-3\left(x^2-1\right)\)

\(=x^2+2x+1-x^2+2x-1-3x^2+3\)

\(=4x+3\)

Answer 2

b) \(5\left(x+2\right)\left(x-2\right)-\frac{1}{2}\left(6-8x\right)+17\)

\(=5\left(x^2-4\right)-3+4x+17\)

\(=5x^2-20-3+4x+17\)

\(=5x^2-6+4x\)