Question

一道初一数学题，求解

当A=3X的平方-2XY+Y的平方
A+2B的值
1/2A-B的值
(3A-B)-(2B-A)
求过程解答
忘了打了 B=X的平方+2XY

Answer 1

A=3x^2-2xy+y^2
B=x^2+2xy
A+2B
=(3x^2-2xy+y^2)+2(x^2+2xy)
=3x^2-2xy+y^2+2x^2+4xy
=5x^2+2xy+y^2
1/2A-B
=1/2(3x^2-2xy+y^2)-(x^2+2xy)
=3/2x^2-xy+1/2y^2-x^2-2xy
=1/2x^2-3xy+1/2y^2
(3A-B)-(2B-A)
=3A-B-2B+A
=4A-3B
=4(3x^2-2xy+y^2)-3(x^2+2xy)
=12x^2-8xy+4y^2-3x^2-6xy
=9x^2-14xy+4y^2
记得采纳哦！~~

Answer 2

A+2B=(3x^2-2xy+y^2)+2(x^2+2xy)
=3x^2-2xy十y^2+2x^2十4xy
=5x^2十2xy十y^2

Answer 3

A=3x^2-2xy+y^2 B=x^2+2xy
=2x^2+x^2-2xy+y^2 =x^2+2xy+y^2-y^2
=2x^2+(x-y)^2 =(x+y)^2-y^2

Answer 4

B是什么
、、、

追问

B=X的平方+2XY