Question

Làm tính nhân:

a,2x⁴+3x²-5x và -x³+2x²-7

b, 4x⁵+2x²- 3x+1 và 2x⁴-3x²+5x²

Answer 1

a: \(\left(2x^4+3x^2-5x\right)\cdot\left(-x^3+2x^2-7\right)\)

\(=-2x^7+4x^6-14x^4-3x^5+6x^4-21x^2+5x^4-10x^3+35x\)

\(=-2x^7+4x^6-3x^5-3x^4-10x^3-21x^2+35x\)

b: \(\left(4x^5+2x^2-3x+1\right)\left(2x^4+2x^2\right)\)

\(=2x^2\left(x^2+2\right)\left(4x^5+2x^2-3x+1\right)\)

\(=2x^2\cdot\left[4x^7+2x^4-3x^3+x^2+8x^5+4x^2-6x+2\right]\)

\(=2x^2\cdot\left(4x^7+8x^5+2x^4-3x^3+5x^2-6x+2\right)\)

\(=8x^9+16x^7+4x^6-6x^5+10x^4-12x^3+4x^2\)