求代数式,[(3m-n)^2-3(3m-2)(m+n)-4mn]/(-二分之一n),其中m.n满足条件m,n满足条件|m-2|+4n^2+4n+1=0

题目

求代数式,[(3m-n)^2-3(3m-2)(m+n)-4mn]/(-二分之一n),其中m.n满足条件m,n满足条件|m-2|+4n^2+4n+1=0

答案

∵m.n满足条件|m-2|+4n^2+4n+1=0
|m-2|+4n^2+4n+1=0
m-2=0 (2n+1)²=0
∴m=2
n=-1/2
∴,[(3m-n)^2-3(3m-2n)(m+n)-4mn]/(-二分之一n),
=(9m²-6mn+n²-9m²-3mn+6n²-4mn)/(-1/2n)
=(-13mn+6n²)/(-1/2n)
=26m-12n
=26×2-12×(-1/2)
=52+6
=58