3X^2(-5X^2my^n)^2
=3x^2(25x^4my^2n)
=75x^(2+4m)y^2n
(-a^3)×(-2ab)^3-3a^2b(a^4b^2+1/2ab^3-1)
=(-a^3)(-8a^3b^3)-3a^2b(a^4b^2+1/2ab^3-1)
=8a^6b^3-3a^6b^3-3/2a^3b^4-3a^2b
=5a^6b^3-3/2a^3b^4-3a^2b
a=1,b=2.
=5(2)^3-3/2(2)^4+3(2)
=40-24+6=22
第二题的简便做法
因为a=1
那么a的n次方都等于1
所以(-a^3)×(-2ab)^3-3a^2b(a^4b^2+1/2ab^3-1),
=(-1)(-2b)^3-3b(b^2+1/2b^3-1)
=8b^3-3b^3-3/2b^4+3b
=64-24-24+6=22