Question

3(ⅹ-5)=12-2(ⅹ+6)求ⅹ()

1、先化简在求值:(x-4)(x-3)-2(x+6)(x-5)其中x=-1
2、给三个多项式1/2a²+2a,1/2a²+3a+2,1/2a²-a,选择两个进行乘法运算

Answer 1

解
(x-4)(x-3)-2(x+6)(x-5)
=(x²-7x+12)-2(x²+x-30)
=(x²-2x²)+(-7x-2x)+(12+60)
=-x²-9x+72
=-1+9+72
=80
选择1/2a²+2a和1/2a²-a
(1/2a²+2a)(1/2a²-a)
=1/4a^4-1/2a³+a³-2a²
=1/4a^4+1/2a³-2a²