已知-m+2n=5,那么3(m-2n)^2+10n-5m-23?
问题描述:
已知-m+2n=5,那么3(m-2n)^2+10n-5m-23?
答
∵-m+2n=5
∴m-2n=-5
3(m-2n)²+10n-5m-23
=3(m-2n)²-5(m-2n)-23
=3×(-5)²-5×(-5)-23
=75+25-23
=77