Question

已知(m-n)的2次方=8,(m+n)的2次方=2,则m的2次方+n的2次方=

Answer 1

(m-n)^2+(m+n)^2=8+2

m^2+n^2-2mn+m^2+n^2+2mn=10

2(m^2+n^2)=10

m^2+n^2=5