Question

(7m的平方-5MN)+2mn-(4m的平方n-3mn) 3a的立方-5a+2-6a的平方+6a-3,其中a=-2

Answer 1

解

(7m²-5mn)+2mn-(4m²n-3mn)

=7m²+(2mn-5mn+3mn)-4m²n

=7m²-4m²n

3a³-5a+2-6a²+6a-3

=3a³-6a²+a-1

=3×(-8)-6×4-2-1

=-24-24-3

=-51

2y²-5xy-(y-7xy+2y²)

=(2y²-2y²)+(7xy-5xy)-y

=2xy-y

=2×(-1/2)×3-3

=-3-3

=-6