已知x^2+xy=6,y^2+xy=10 求(1)(x+y)^2 (2)x^2-y^2 (3)(x-y)2已知x^2+xy=6,y_数学解答

已知x^2+xy=6,y^2+xy=10 求(1)(x+y)^2 (2)x^2-y^2 (3)(x-y)2
已知x^2+xy=6,y^2+xy=10 求(1)(x+y)^2 (2)x^2-y^2 (3)(x-y)^2

人气：408 ℃　时间：2020-02-05 03:27:21

解答

(x+y)^2
=x^2+2xy+y^2
=x^2+xy+y^2+xy
=6+10
=16
x^2-y^2
=x^2+xy-(y^2+xy)
=6-10
=-4
(x-y)^2
=((x^2-y^2)/(x+y))^2
=(x^2-y^2)^2/(x+y)^2
=(-4)^2/16
=1