Question

已知x+y=8,x^3+x^3=40,求x^2+y^2的值

Answer 1

题目似乎应该改为x^3+y^3=40

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

即 40 - 8 = 8 *(x^2+y^2-1)

所以x^2+y^2=5