Question

rút gọn biểu thức 

a) (3x-1)²-5(x-2)(x+2)+6(x-1) 

b) (5x-2)²-3(2x-3)(2x+3)-(4x-2)(x+1) 

Answer 1

a: \(=9x^2-6x+1-5x^2+20+6x-6\)

\(=4x^2+15\)

b: \(=25x^2-20x+4-3\left(4x^2-9\right)-\left(4x^2+4x-2x-2\right)\)

\(=25x^2-20x-4x^2-2x+2-12x^2+27+4\)

\(=9x^2-22x+33\)

Answer 2

a.

\(=\left(3x\right)^2-2.3x.1-5.\left(x^2-2^2\right)+6x-6\)

\(=9x^2-6x-5x^2+20+6x-6\)

\(=4x^2+14\)

b.

\(=\left(5x\right)^2-2.5x.2-3\left[\left(2x\right)^2-3^2\right]-\left(4x^2+4x-2x-2\right)\)

\(=25x^2-20x-3\left(4x^2-9\right)-4x^2-4x+2x+2\)

\(=25x^2-20x-12x^2+27-4x^2-4x+2x+2\)

\(=9x^2-22x+29\)