Question

初一数学+英语

单复句子互换
This is my brother
This is his cousin
These are ID card
Those are baseballs
Is yhis your faher?

数学题写过程
X-[y-2x-(x-y)}
2(a²b-3ab²)-3(2a²b-7ab²)
一直m²与-2n²的和为A，1+n²与-2m²的差为B，求2A-4B
先化简再求值：4X²Y-{6xy-3（4xy-2）-x²y｝+1其中x=2，y=二分之一
由于看错了符号，某学生把一个多项式减去x²+6x-6误当成了加法计算，结果得到2x²-2x+3，正确的结果应该是多少？

Answer 1

我是个高中生，下面为你解答
These are my brothers
These are his cousins
This is ID card
That is baseball
Are these your fathers？ 很简单的
下面是数学
X-[Y-2X-(X-Y)]=X-Y+2X+(X-Y)=X-Y+2X+X-Y=4X-2Y 注意式子钱为-要加变减 减变加 +则不用 照抄就行
2(a2b-3ab2)-3(2a2b-7ab2)=2a2b-6ab2-6a2b+21ab2=15ab2-4a2b=还可以把ab提出来=ab（15b-4a）
m2与-2n2的和为A ∴A=m2-2n2 1+n2与-2m2的差为B ∴ B=1+n2+2m2
2A-4B=2（m2-2n2）-4（1+n2+2m2）=-6m2-4n2-4
4X2Y-{6xy-3（4xy-2）-x2y｝+1=3x2y+6xy-5 又x=2 y=? ∴原式=6+6-5=7
最后一题 设原来的多项式为A ∴A+x2+6x-6=2x2-2x+3 A=x2-8x+9
∴A-（x2+6x-6）=x2-8x+9-x2-6x+6=15-14x

Answer 2

本人数学不太好，只能提供英语方面的帮助
These are my brothers
These are his cousins
This is ID card
That is baseball
Are these your fathers?
说实话，这几句英语很简单，你上课时没有注意听吧！
单复数的转换是这个单元的重点，多复习几遍。

Answer 3

英语:
注意单复数转换时量词不能弄错
These are my brothers
These are his cousins
This is a ID card
That is a baseball
Are these your fathers?

数学
X-[Y-2X-(X-Y)]=X-Y+2X+(X-Y)=X-Y+2X+X-Y=4X-2Y 注意式子钱为-要加变减 减变加 +则不用 照抄就行
2(a2b-3ab2)-3(2a2b-7ab2)=2a2b-6ab2-6a2b+21ab2=15ab2-4a2b=还可以把ab提出来=ab（15b-4a）
m2与-2n2的和为A ∴A=m2-2n2 1+n2与-2m2的差为B ∴ B=1+n2+2m2
2A-4B=2（m2-2n2）-4（1+n2+2m2）=-6m2-4n2-4
4X2Y-{6xy-3（4xy-2）-x2y｝+1=3x2y+6xy-5 又x=2 y=? ∴原式=6+6-5=7
最后一题 设原来的多项式为A ∴A+x2+6x-6=2x2-2x+3 A=x2-8x+9
∴A-（x2+6x-6）=x2-8x+9-x2-6x+6=15-14x