Bài 2:
a) Ta có: \(\left(3x-2\right)\left(2x-1\right)+\left(5-x\right)\left(6x+2\right)\)
\(=6x^2-3x-4x+2+30x+10-6x^2-2x\)
\(=21x+12\)
b) Ta có: \(3\left(x-1\right)\left(2x+3\right)-\left(x-2\right)\left(6x+1\right)\)
\(=3\left(2x^2+3x-2x-3\right)-\left(6x^2+x-12x-2\right)\)
\(=6x^2+3x-9-6x^2+11x+2\)
=14x-7
c) Ta có: \(\left(5x+1\right)\left(2x-3\right)-10x\left(x-1\right)\)
\(=10x^2-15x+2x-3-10x^2+10x\)
\(=-3x-3\)
d) Ta có: \(\left(x-3\right)\left(4x+5\right)-4\left(x+2\right)\left(x+1\right)\)
\(=4x^2+5x-12x-15-4\left(x^2+3x+2\right)\)
\(=4x^2-7x-15-4x^2-12x-8\)
=-19x-23
Bài 3:
b) Ta có: \(x\left(2x^2-3\right)-x^2\left(2x-1\right)\)
\(=2x^3-3x-2x^3+x^2\)
\(=x^2-3x\)
d) Ta có: \(\left(-2x-3\right)\left(x^2-1\right)+\left(x-2\right)\left(2x^2+1\right)\)
\(=-2x^3+2x-3x^2+3+2x^3+x-4x^2-2\)
\(=-7x^2+3x+1\)
Bài 4:
b) Ta có: \(\left(x-2\right)\left(x+2\right)-\left(x-5\right)^2\)
\(=x^2-4-x^2+10x-25\)
=10x-29
d) Ta có: \(\left(2x+1\right)^2-\left(2x+3\right)\left(2x-3\right)\)
\(=4x^2+4x+1-4x^2+9\)
=4x+10
Bài 1:
a) Ta có: \(2x\left(1-x\right)+x\left(2x-3\right)\)
\(=2x-2x^2+2x^2-3x\)
=-x
b) Ta có: \(3x\left(2x-5\right)-2x\left(3x-4\right)\)
\(=6x^2-15x-6x^2+8x\)
=-7x
