作业帮mn+3n+3m+9
来源：学生作业帮助网 编辑：作业帮 时间：2024/05/12 19:42:08
先合并同类项,得3(m-n)-6mn+9,代入已知数据,有结果27
-9m²n+36mn-3n=-3n(3m²-12m+1)再问：再问两题~，是化简分式：（1）1/2x-1/3y分之1/2x+1/3y（2）1/x²-1/y²分之1/x-1/y谢谢~再答：（1）(1/2
再答：谢谢
2[mn+(-3m)]-3(2n-mn)=2mn-6m-6n+3mn=5mn-6m-6n=5mn-6(m+n)m+n=2mn=-3=-15-12=-27
3(m^2n+mn)-4(mn-2m^2n)+mn.=3m^2n+3mn-4mn+8m^2n+mn.=11m^2n.
再答：错了再答：后面是3（m－n）再答：是15＋12＝27再问：谢谢了
（9-2mn+2m+3n)-(m+4n+mn）=9-2mn+2m+3m-m-4n-mn=9-mn+(m-n)=9-(-1)+4=14
3m^2-mn/9m^2-6mn+n^2=m(3m-n)/(3m-n)^2=m/(3m-n)=3n/(9n-n)=3/8
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
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
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+3-1/m)=(3/2-5)/(-1/2+
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+n)+6(m+n)]=[-7(m+n)
-3m^2+9mn+12n^2=-3(m²-3mn-4n²)=-3(m+n)(m-4n)
（9-2mn+2m+3n)-(3mn+2n-2m)-(m+4n+mn)=9-2mn+2m+3n-3mn-2n+2m-m-4n-mn=9-6mn+3m-3n=9-6mn+3(m-n)=9-6×（-1）+3×4=9+6+12=27
原式=-2mn+2m+3n-3mn-2n+2n-m-4n-mn=-6mn+m-n=-6×2+4=-8
(3m--2n)^2+24mn=9m^2--12mn+4n^2+24mn=9m^2+12mn+4n^2=(3m+2n)^2.
=m^2n^2×(-m^6n^3)=-m^8n^5
(-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=27
【2m²n-3mn²】÷【mn】=2m-3n
-2mn+2m+3n-3mn-2n+2m-4n-m-mn=-6mn+3m-3n=-6mn+3(m-n)=6+9=15