=3x^2-xy-2y^2
=(3x+2y)(x-y)
A-2B=2x^2-3xy+y^2-2(x^2+2xy-3y^2)
=2x^2-3xy+y^2-2x^2-4xy+6y^2
=-7xy+7y^2
=7y(y-x)追问
^是什么？
追答x^2表示x的平方
=3x^2-xy-2y^2
=(3x+2y)(x-y)
A-2B=2x^2-3xy+y^2-2(x^2+2xy-3y^2)
=2x^2-3xy+y^2-2x^2-4xy+6y^2
=-7xy+7y^2
=7y(y-x)
已知A=2x的2次方-3xy+y的2次方,B=x的2次方+2xy-3y的2次方,求A+B;A...
A+B=2x^2-3xy+y^2+x^2+2xy-3y^2 =3x^2-xy-2y^2 =(3x+2y)(x-y)A-2B=2x^2-3xy+y^2-2(x^2+2xy-3y^2)=2x^2-3xy+y^2-2x^2-4xy+6y^2 =-7xy+7y^2 =7y(y-x)
已知:A=2x^2-3xy+2y^2,B=2x^2+xy-3y^2 求①A+B ②A-(B-2A)
A=2x^2-3xy+2y^2,B=2x^2+xy-3y^2 求①A+B ②A-(B-2A)①A+B =2x^2-3xy+2y^2+2x^2+xy-3y^2 =4x^2-2xy-y^2 ②A-(B-2A)=A-B+2A =3A-B =3(2x^2-3xy+2y^2)-(2x^2+xy-3y^2 )=6x^2-9xy+6y^2-2x^2-xy+3y^2 =4x^2-10xy+9y^2 ...
已知A=2x的平方减x+y-+3+xyb=x^2-2+x-y+xy化简a-+2b?
∵a=2x^2一x+y一3+ⅹy，b=x^2一2+ⅹ一y+xy，∴a一2b =(2x^2一x+y一3+ⅹy)一2(x^2一2+x一y+ⅹy)=2ⅹ^2一ⅹ+y一3+xy一2x^2+4一2x+2y一2xy =一3x+3y一xy+1。
已知A=2X的2次方-3XY,B=X的2次方+2XY-4Y的2次方,则A-2B=?快呀急急急...
A-2B =2x²-3xy-(2x²+4xy-8y²)=2x²-3xy-2x²-4xy+8y²=-7xy+8y²
已知A=2x²-3xy+y²,B=x²+2xy-3y²,求:(1)A+B;(2)A-2B
（1）A+B= 2x²-3xy+y²+x²+2xy-3y²整理得 A+B=3x方-xy-2y方 （2）A-2B= 2x²-3xy+y²-2（x²+2xy-3y²）整理得 -7xy+4y方 谢谢采纳 如果满意请采纳！如果不懂继续追问 我随时回答 谢谢！！
以知多项式A=x的2次方-3xy+y的2次方,B=2x的2次方+2xy-3y的2次方 求A...
因为A＝x²－3xy+y²，B＝2x²+2xy-3y²所以A+B=x²－3xy+y²+2x²+2xy-3y²=3x²-xy-2y²A-2B=x²－3xy+y²-2(2x²+2xy-3y²)=x²－3xy+y²-4x²-4xy+6y²=-3x²-...
已知A=2x2-3xy+y2,B=x2-2xy+y2,求:A+B,A-B.
分析：根据A=2x2-3xy+y2，B=x2-2xy+y2，列出A+B，A-B的式子，再去括号，合并同类项即可．解答：解：∵A=2x2-3xy+y2，B=x2-2xy+y2，∴A+B=（2x2-3xy+y2）+（x2-2xy+y2）=2x2-3xy+y2+x2-2xy+y2 =3x2-5xy+2y2；A-B=（2x2-3xy+y2）-（x2-2xy+y2）=2x...
已知A=2x^2-3xy-y^2,B=-3y^2+2xy+x^2,求2A-(2B+A)的值,其中x=y=-2...
解: a=B-2A=(4x²-6xy+2y²-3x-y)-2*(2x²-3xy+y²-x+2y)=4x²-6xy+2y²-3x-y-4x²+6xy-2y²+2x-4y =-x-5y 因为\/x-2a\/+(y+3)²=0 所以 (y+3)²=0 解得y=-3 \/x-2a\/=0 \/x-2(-x-5y)\/=\/x+2x+10y\/...
已知a=2x²-3xy+y²,b=x²+2xy-3y²,化简:(1)a+b (2)a-2b...
a+b =2x²-3xy+y²+x²+2xy-3y²=3x²-xy-2y²a-2b =2x²-3xy+y²-2(x²+2xy-3y²)=2x²-3xy+y²-2x²-4xy+6y²=-7xy+7y²
已知A=2x的平方-3xy-y的平方,B=-3y的平方+2xy+x的平方,求2A-(2B+A...
2A-(2B+A)=2A-2B-A =A-2B =2x^2-3xy-y^2-2(-3y^2+2xy+x^2)=2x²-3xy-y²+6y²-4xy-2x²=-7xy+5y²=-7×4+5×4 =-28+20 =-8
