(m+n)²-(m-n)²

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(m+n)²-(m-n)²

(m+n)²-(m-n)²
(m+n)²-(m-n)²

(m+n)²-(m-n)²
(m+n)²-(m-n)²
=m²+n²+2mn-(m²+n²-2mn)
=2mn-(-2mn)
=4mn
还望采纳哟!

绝对是4mn

(m+n)²-(m-n)²
=[(m+n)+(m-n)]*[(m+n)-(m-n)]
=[2m]*[2n]
=4mn

=m*2+n*2+2mn-m*2-n*2+2mn=4mn