Question

已知(m-n)^2=8,(m+n)^2=2则m^2+n^2的值是多少

Answer 1

(m-n)^2+(m+n)^2=8+2
m^2-2mn+n^2+m^2+2mn+n^2=10
2m^2+2n^2=10
所以m^2+n^2=5

Answer 2

(m-n)^2=8,(m+n)^2=2
(m-n)^2-(m+n)^2= -4mn= 6
mn= -1.5
m^2+n^2 = (m-n)^2 +2mn
= 8-3
=5

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Answer 3

我们今天也写的作业

Answer 4

(m-n)^2+(m+n)^2=8+2
m^2-2mn+n^2+m^2+2mn+n^2=10
2m^2+2n^2=10
所以m^2+n^2=5

Answer 5