Question

1) (\(\dfrac{1}{2}\)x + 3)*(x²- 4x- 6)

2) (6x² -9x +15)*(\(\dfrac{2}{3}\)x+1)

3) (3x² -x+5)*(x³+5x-1)

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

5) D=(x-7)*(x+5)-(x-4)*(x+3)

6) E= 4x*(x²-x-1)-(x+3)*(x²-2)

7) F= 5x*(x-3)*(x-1)-4x*(x²-2x)

Answer 1

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

\(=\dfrac{1}{2}x^3-2x^2-3x+3x^2-12x-18\)

\(=\dfrac{1}{2}x^3+x^2-15x-18\)

2) \(\left(6x^2-9x+15\right)\left(\dfrac{2}{3}x+1\right)\)

\(=4x^3+6x^2-6x^2-9x+10x+15\)

\(=4x^3+x+15\)

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

\(=3x^5+15x^2-3x^2-x^4-5x^2+x+5x^3+25x-5\)

\(=3x^5-x^4+5x^3+10x^2+26x-5\)

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

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

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