已知m+n=5,mn=3,求m^4+n^4的值

(m+n)^2=5^2
m^2+2mn+n^2=25
m^2+n^2=25-2mn=25-6=19
(m^2+n^2)^2=19^2
m^4+2m^2n^2+n^4=361
m^4+n^4=361-2(mn)^2=343

(m+n)^2=25
m^2+n^2+2mn=25
m^2+n^2=19,
(m^2+n^2)^2=361,
m^4+n^4+2(mn)^2=361,
m^4+n^4=343

m^4+n^2=(m^2+n^2)^2-2m^2n^2=[(m+n)^2-2mn]^2-2(mn)^2=[5^2-6]^2-18=343

m^4+n^4 ＝ (M^2+n^2)^2 - 2(mn)^2
=( (M+n)^2 - 2mn )^2 - 2(mn)^2
=( 5^2 - 2*3 )^2 - 2*(3)^2
没带计算器了 楼主自己按吧＾＾
不好意思～

^这个符号是什么意思