已知-m+2n=2,求5(m-2n)²+6n-3m-3的值
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已知-m+2n=2,求5(m-2n)²+6n-3m-3的值
已知-m+2n=2,求5(m-2n)²+6n-3m-3的值
已知-m+2n=2,求5(m-2n)²+6n-3m-3的值
5(m-2n)²+6n-3m-3
=5[-(-m+2n)]²+3(-m+2n)-3
=5*(-2)²+3*2-3
=20+6-3
=23
原式=5(2n-m)^2+2(2n-m)-3
=5*4+2*2-3=21