1:已知x=y+3,求代数式¼(x-y)²+(3/10)乘(x-y)+¾(x-y)²+(7/10)乘(x-y)+2的值?
问题描述:
1:已知x=y+3,求代数式¼(x-y)²+(3/10)乘(x-y)+¾(x-y)²+(7/10)乘(x-y)+2的值?
2:计算:(1)(3x²-y²-2xy)+(y²-xy-2x²);(2)(8ab-a²+b²)-(a²-b²+8ab);
(3)5(11x³-2x²)+2(x³+5x²); (4)2(2/3)x³y-2y²)-3(-x³y+2y²+1);
(5)3ab-{3ab+[5a²b+(3ab-2²b]}-5a²b;(6)xy-{4x²y-[3x²y-(2xy-x²y)+3xy]}.
答
1、=(1/4+3/4)(x-y)+(3/10+7/10)(x-y)+2=2(x-y)+2=2*3+2=82的计算呢???把括号去掉有些就相消了