Question

数学高手进！！

计算：
(1-y)^2+(1+y)^2

(2-y)^2-(2+y)^2

2(x+y)^2-2y(y+2x)

3(a-2b)^2-12b(a+b)

写过程！！高分悬赏！！！
(1-y)^2=(1-y)的2次方！！

Answer 1

(1-y)^2+(1+y)^2
=1+y²-2y+1+y²+2y
=2+2y²=2(1+y²)

(2-y)^2-(2+y)^2
=4+y²-4y-(4+y²+4y)
=-8y

2(x+y)^2-2y(y+2x)
=2(x²+y²+2xy)-2y²-4xy
=2x²

3(a-2b)^2-12b(a+b)
=3(a²+4b²-4ab)-12ab-12b²
=3a²-24ab
=3a(a-8b) 回答者： 热心网友 | 2011-3-3 18:20 | 检举

这个就是我答的忘记登录了

Answer 2

第一个1-2y+y^2+1+2y+y^2=2+2y^2第二个4-4y+y^2-4-4y-y^2=-4y^2第三个2(x^2+y^2+2xy-2y^2-4xy=2x^2第四个3(a^2-4ab+4b^2)-12ab-12b^2=3a^2-28ab

Answer 3

(1-y)^2+(1+y)^2
=1+y²-2y+1+y²+2y
=2+2y²=2(1+y²)

(2-y)^2-(2+y)^2
=4+y²-4y-(4+y²+4y)
=-8y

2(x+y)^2-2y(y+2x)
=2(x²+y²+2xy)-2y²-4xy
=2x²

3(a-2b)^2-12b(a+b)
=3(a²+4b²-4ab)-12ab-12b²
=3a²-24ab
=3a(a-8b)

Answer 4

(1-y)^2+(1+y)^2=1-2y+y^2+1+2y+y^2=2+2y^2

(2-y)^2-(2+y)^2=4-4y+y^2-4-4y-y^2=-4y

2(x+y)^2-2y(y+2x)=2(x^2+2xy+y^2)-2y^2-4xy=2x^2

3(a-2b)^2-12b(a+b)=3(a^2-4ab+4b^2)-12ab-12b^2=3a^2-24ab