3a^2-a(3a-5b)-b(2a-b)^2.计算
=3a^2-3a^2+5ab-4a^2b+4ab^2-b^3
=5ab-4a^2b+4ab^2-b^3
(a+3)^2*(a^2+9)^2*(a-3)^2.计算
=[(a-3)(a+3)(a^2+9)]^2
=[(a^2-9)(a^2+9)]^2
=(a^4-81)^2
=a^8-162a^4+6561
(2a^3b^3-3b)*(-1/2b^2).计算
=-a^3b^5+(3/2)b^3
x^2-3x+1=0
x不等于0
所以两边除以x
x-3+1/x=0
x+1/x=3
(1) x^2+1/x^2
x+1/x=3
两边平方
x^2+2+1/x^2=9
x^2+1/x^2=7
(2) (x^4+x^2+1)/(x^2)
=x^2+1+1/x^2
=7+1=8