1.已知a+5b=6.求a²+5ab+30b的值.

题目

1.已知a+5b=6.求a²+5ab+30b的值.
2.1+x+x²+x^3=0,求x+x^2+x^3+x^4+x^5+x^6+x^7+x^8的值.

答案

a²+5ab+30b=a﹙a＋5b﹚＋30b=6a＋30b=6﹙a＋5b﹚=36
x+x^2+x^3+x^4+x^5+x^6+x^7+x^8
=x﹙1＋x+x^2+x^3﹚+x^5﹙1＋x+x^2+x^3﹚
=0＋0
=0