Question

Bài 2: Làm tính nhân : 

1) (\(\dfrac{3}{2}\)x-1).(-4x²+2x-6)

2) (-\(\dfrac{2}{3}\)x+3)(3x²-6x+9)

3)(x³-2x²+x-1)(5-x)

4) (x-1) (x+1)(x+2)

5)(x-\(\dfrac{1}{2}\))(x+\(\dfrac{1}{2}\))(4x-1)

Answer 1

1: \(\left(\dfrac{3}{2}x-1\right)\left(-4x^2+2x-6\right)\)

\(=-6x^3+3x^2-9x+4x^2-2x+6\)

\(=-6x^3+7x^2-11x+6\)

2: \(\left(-\dfrac{2}{3}x+3\right)\left(3x^2-6x+9\right)\)

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

\(=-2x^3+4x^2-6x+9x^2-18x+27\)

\(=-2x^3+13x^2-24x+27\)

3: \(\left(x^3-2x^2+x-1\right)\left(5-x\right)\)

\(=5x^3-x^4-10x^2+2x^3+5x-x^2-5+x\)

\(=-x^4+7x^3-11x^2+6x-5\)

4: \(\left(x-1\right)\left(x+1\right)\left(x+2\right)\)

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

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

5: \(\left(x-\dfrac{1}{2}\right)\left(x+\dfrac{1}{2}\right)\left(4x-1\right)\)

\(=\left(x^2-\dfrac{1}{4}\right)\left(4x-1\right)\)

\(=4x^3-x^2-x+\dfrac{1}{4}\)