已知m n=2008,m-n=-1,求m的平方-n的平方的值
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m+n=2mn=-42(mn-3m)-3(2n-mn)=2mn-6m-6n+3mn=5mn-6(m+n)=-20-12=-32
由于:mn/(m+n)=2则有:mn=2(m+n)则:原式=(3m+3n-5mn)/(-m-n+3mn)=[3(m+n)-5mn]/[-(m+n)+3mn]=[3(m+n)-10(m
(2mn+2m+3n)-(3mn+2n-2m)-(m+4n+mn)先去括号=2mn+2m+3n-3mn-2n+2m-m-4n-mn合并同类项=-2mn+3m-3n=-2mn+3(m-n)把m-n=2,
=m^2-2mn+n^2+mn(前面多减一个配成完全平方,后面再加一个)=(m-n)^2+mn=(m+n)^2+5mn=81+70=151
m^2-mn-n^2+3mn-3mn=(m+n)^2-3mn=81-3*14=39
同学,你题目应该是写错了应该是这样的吧mxm+mn+m=14nxn+mn+n=28两列相加,得mxm+nxn+2mn+m+n=42得(m+n)(m+n)+m+n=42得m+n=6或m+n=-7
3m-5mn+3n/(-m)+3mn-n=【3(m+n)-5mn】/【3mn-(m+n)】=【3-5mn/(m+n)】/【3mn/(m+n)-1】=【3-5x2】/【3x2-1】=-7/5
解(-2mn+2m+3n)-(3mn+2n-2m)-(m+4n+mn)=-2mn+2m+3n-3mn-2n+2m-m-4n-mn=-2mn-3mn-mn+2m+2m-m+3n-2n-4n=-6mn+3
答:mn/(m+n)=2分子分母同除以mn得:1/(1/n+1/m)=21/m+1/n=1/2(3m-5mn+3n)/(-m+3mn-n)分子分母同除以mn得:=(3/n-5+3/m)/(-1/n+3
由于:mn/(m+n)=2则有:mn=2(m+n)则:原式=(3m+3n-5mn)/(-m-n+3mn)=[3(m+n)-5mn]/[-(m+n)+3mn]=[3(m+n)-10(m+n)]/[-(m
m²-mn=15==>3m²-3mn=45(1)mn-n²=-6==>2mn-2n²=-12(2)(1)式+(2)式==>3m²-mn-2n²
因为m-mn=21,mn-n=15,所以:m-n=(m-mn)+(mn-n)=21+15=36m-2mn+n=(m-mn)-(mn-n)=21-15=6希望能都帮到你,追问:对不起啊.我把题发错了,m
m^2-mn=21,①mn-n^2=-12.②①+②得:m^2-n^2=21-12=9有不懂的可以问我!
-MN(M^2N^5-MN^3-N)=-(-6)^3+(-6)^2-(-6)=258
-2mn+2m+3n-3mn-2n+2m-4n-m-mn=-6mn+3m-3n=-6mn+3(m-n)=6+9=15
m²+(n-mn)²+2mn-2m²n=m²+n²-2mn²+m²n²+2mn-2m²n=m²+2m
原式=-2mn+2m+3n-3mn-2n+2n-m-4n-mn=-6mn+m-n=-6×2+4=-8
知m-n=7,mn=2求5n-3mn+5m+2(m+n)²=(m-n)²+4mn=49+8=57m+n=正负根号575n-3mn+5m+2=5n+5m-3mn+2=5(m+n)-3
∵原式=-3(2n-mn)+2(mn-3m)=-6(m+n)+5mn∵m+n=-3,mn=2∴原式=-6·-3+5·2=28
(-m-4n-mn)-(2mn-2m-3n)-(3mn+2n-2m)=-m-4n-mn-2mn+2m+3n-3mn-2n+2m=3m-3n-6mn=3(m-n)-6mn=3×3-6×(-3)=9+18