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
