已知m-n=3,求代数式m2-n2+2m-8n-4的值

问题描述:

已知m-n=3,求代数式m2-n2+2m-8n-4的值

m2-n2+2m-8n-4
=(m-n)(m+n)+2m-8n-4
=3m+3n+2m-8n-4
=5m-5n-4
=5(m-n)-4
=15-4
=11