先化简再求值:6m^2-5m(-m+2n-1)+4m(-3m-5/2n-3/4),其中m=-1,n=1/20

学习 时间:2026-06-05 17:47:31 阅读:3957
先化简再求值:6m^2-5m(-m+2n-1)+4m(-3m-5/2n-3/4),其中m=-1,n=1/20

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洁净的灯泡

风趣的月光

2026-06-05 17:47:31

6m^2-5m(-m+2n-1)+4m(-3m-5/2n-3/4)=6m²+5m²-10mn+5m-12m²-10mn-3m=﹣m²-20mn+2m=﹣m(m+20n-2)再将m=-1,n=1/20代入有原式=﹣m(m+20n-2) =﹣(﹣1)[(﹣1)+20×1/20-2] =﹣2

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  • 可靠的雪糕
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    2026-06-05 17:47:31

    6m^2-5m(-m+2n-1)+4m(-3m-5/2n-3/4)=6m²+5m²-10mn+5m-12m²-10mn-3m=﹣m²-20mn+2m=﹣m(m+20n-2)再将m=-1,n=1/20代入有原式=﹣m(m+20n-2) =﹣(﹣1)[(﹣1)+20×1/20-2] =﹣2

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