Question

初一下学期数学：若A=-2x,B=1/2x²+3x-1,求(1)A² *B (2)3A* B -A*( B -A)

Answer 1

(1)A² *B
=(-2x)²(1/2x²+3x-1)
=4x²(1/2x²+3x-1)
=2x的4次方+12x³-4x²

(2)3A* B -A*( B -A)
=3AB-AB+A²
=2AB+A²
=2×(-2x)×(1/2x²+3x-1)+(-2x)²
=-2x³-12x²+4x+4x²
=-2x³-8x²+4x

Answer 2

A=-2x,B=1/2x²+3x-1,

(1)A² *B
=(-2x)² * (1/2x²+3x-1)
=4x² * (1/2x²+3x-1)
=2x^4+12x³-4x²

(2)3A* B -A*( B -A)

=3AB-AB+A²
=2AB+A²
=2×(-2x)×(1/2x²+3x-1)+4x²
=-2x³-12x²+4x+4x²
=-2x³-8x²+4x

Answer 3

(1)A² *B
=(-2x)²*(1/2x²+3x-1)
=2x^4+12x³-4x²

(2)3A* B -A*( B -A)
=3*(-2x)*(1/2x²+3x-1)-(-2x)(1/2x²+3x-1+2x)
=-3x³-18x²+6x+x³+6x²-2x+4x
=-2x³-12x²+8x