Question

求这些道题的过程和答案

Answer 1

解答：

11.  (1) (-4a)*(5a²-6a+1)=-20a³+24a²-4a

(2) 3x[(1/3)x²-1]-5x[(1/5)x²+2/5)=x³-3x-x³-2x=-5x

(3) (3x+2y)(9x²-6xy+4y²)=27x³-18x²y+12xy²+18x²y-12xy²+8y³=27x³+8y³

(4) (3a+2)(a-4)-3(a-2)(a-1)=3a²-12a+2a-8-3(a²-3a+2)=-a-14

12.需要C类卡片11张

13. 已知：ab=a+b+2021，

则（a-1)*(b-1)=ab-a-b+1=a+b+2021-a-b+1

=2022

14.已知x²-x-1=0，则代数式-x³+2x²+2021

=-x(x²-x-1)+x²-x-1+2022=2022