先化简再求值[(m+n)(m-n)-(m-n)²]÷(2n),其中m=-2,n=-1/2
问题描述:
先化简再求值[(m+n)(m-n)-(m-n)²]÷(2n),其中m=-2,n=-1/2
答
[(m+n)(m-n)-(m-n)²]÷(2n)
=[m²-n²-(m²-2mn+n²)] ÷(2n)
=(2mn-2n²)÷2n
=m-n
=-3/2
答
[(m+n)(m-n)-(m-n)²]÷(2n)
=[(m+n-m+n)(m-n)]÷(2n)
=2n(m-n)÷(2n)
=m-n
=-2-(-1/2)
=-3/2