若M的2次方与-2N的2次方的和为M,1+n的2次方与-2m次方的差为n,试求2m-4n?

2025-02-26 17:57:16
推荐回答(1个)
回答1:

M=m²-2n²
N=1+n²+2m²
则2M-4N
=2(m²-2n²)-4(1+n²+2m²)
=2m²-4n²-4-4n²-8m²
=-6m²-8n²-4