已知:x+y=1,xy=-3,求下列各式的值: (1)x2+y2; (2)x3+y3; (3)x5y+xy5.

只答2,3题,急
2025-05-16 11:10:57
推荐回答(2个)
回答(1):

(1)x^2+y^2=(x+y)^2-2xy
=1-(-3)
=1+3
=4
(2)x^3+y^3=(x+y)(x^2-xy+y^2)
=(x^2-xy+y^2)
=(x^2+2xy+y^2)-3xy
=(x+y)^2-3xy
=1-3*(-3)
=10

回答(2):