m-n=7,mn=6,m^2+n^2

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m-n=7,mn=6,m^2+n^2
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m-n=7,mn=6,m^2+n^2
m-n=7,mn=6,m^2+n^2

m-n=7,mn=6,m^2+n^2
m^2+n^2
=(m-n)^2+2mn
=7^2+2*6
=49+12
=61

等于61
前面的括号的平方+2倍的mn

m²+n²
=m²-2mn+n²+2mn
=(m-n)²+2mn
=7²+2x6
=61

m^2+n^2=(m-n)^2+2mn=49+12=61

m-n=7
(m-n)²=7²
m²-2mn+n²=49
(m²+n²)-2mn=49
将mn=6代入(m²+n²)-2mn=49,得:
(m²+n²)-2×6=49
(m²+n²)-12=49
m²+n²=49+12
m²+n²=61