原式=4xy-[x2+5xy-y2-2x2-6xy+y2]
=4xy-[-x2-xy]
=x2+5xy,
当x=-1,y=2时,
原式=x2+5xy
=(-1)2+5×(-1)×2
=-9.
先化简,再求值.4xy-[(x2+5xy-y2)-2(x2+3xy-1/2y2)],其中:x=-1,y=2.
先化简,再求值.4xy-[(x2+5xy-y2)-2(x2+3xy-
y2)],其中:x=-1,y=2.
1 |
2 |
数学人气:119 ℃时间:2020-01-30 00:33:33
优质解答
我来回答
类似推荐
猜你喜欢
- 1帮我解决几个英语题目:1.A___,please!I have something important to tell you.
- 2They have some erasers改为单数形式.
- 3社会选择题、判断题、填空题
- 4定义在R上的奇函数f(x)以2为周期,则f(1)+f(2)+f(3)的值是( ) A.0 B.1 C.2 D.3
- 5Great Britain is an island that lies off the northwest coast of Europe .The nearest country is Fra
- 6将2167800改写为用“万”作单位的数是()万,保留一位小数约是()万;改写为用“亿”作单位的
- 7描写祖国边塞风光的诗词
- 8若关于x的一元一次方程2x-k÷3=1+x-3k÷2的解是x=-1,则k=()
- 9What's the ___ ___this?(What's this in English?)
- 10有一张长方形的纸,长10厘米,宽8厘米.在纸的一角剪去一个边长是4厘米的正方形,剩下图形的周长