Question

x+y=6 xy=-4，x是多少，y是多少

Answer 1

t^2-6t+4=0t1+t2=6     t1t2=4t=(3±√5)x=3+√5    y=3-√5或x=3-√5    y=3+√5

Answer 2

Answer 3

X=3+√13或3-√13。Y跟X一样。