题目

1.-3x^2×（-2x^2+1/4x-1）
2.(-5x^2)×(-2y)+3xy(1-3x)
3.(-4a^2b)^2×(1/2a^2b^2-3ab-5b^2)
4.5x^3×x^2+(-3x^3)^2-(-x^2)^3

提问时间：2020-08-10

答案

1.-3x^2×（-2x^2+1/4x-1）
=6x^4 - (3/4)·x³ + 3x²
.
2.(-5x^2)×(-2y)+3xy(1-3x)
=5x²y +3xy-9x²y
=-4x²y +3xy
=xy(-4x+3)
.
3.(-4a^2b)^2×(1/2a^2b^2-3ab-5b^2)
=-2a^4·b^4 + 12a³b³ + 20a²b^4
.
4.5x^3×x^2+(-3x^3)^2-(-x^2)^3
=5x^5 + 9x^6 +x^6
=5x^5 + 10x^6
=5x^5·(1+2x)