4m²-9分之3mn与2m 3分之2mn

因为|m-n-2|大于等于0(mn-1）的2次方大于等于0且|m-n-2|与(mn-1）的2次方互为相反数所以m-n-2=0mn-1=0则m-n=2mn=1(-2mn+2m+3n)-(3mn+2n-2

3(m^2+mn)-4(mn-2m^2n)+mn=3m²+3mn-4mn+2m²n+mn=3m²+2m²n=m²(3+2n)

“liljw0924”：二个数的分母分别为4m²-9和2m+34m²-9=（2m）²-3²=（2m+3）×（2m-3）它们的公分母是（2m+3）×（2m-3）通

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)m²n+3mn²分之m²+3mn原式=m（m+3n）/mn（m+3n）=1/n（2）x²+6x+9分之x²-9原式=(x+3)(x-3)/(x+

先合并同类项,得3(m-n)-6mn+9,代入已知数据,有结果27

原式=(3m-n)²分之m(3m-n)=(3m-n)分之m=(3*1-2)分之1=1

4m²-9=(2m+3)(2m-3)所以最简公分母就是4m²-9所以(2m-3)/(2m+3)=(2m-3)²/(4m²-9)

m3-3mn+n3=(m2)*m-3mn+(n2)*n=(n+2)m-3mn+(m+2)n=mn+2m-3mn+mn+2n=2(m+n)-mn又因为m2=n+2,n2=m+2相减得到：m2-n2=(m

解最简公分母2(x+y)²,∴(x-y)/(2x+2y)=(x+y)(x-y)/2(x+y)²=(x²-y²)/2(x+y)²xy/(x+y)

［（m－n）/（m^2－2mn＋n^2）－（mn＋n^2）/（m^2－n^2）］［mn/（n－1）］＝｛（m－n）/（m－n）^2－n（m＋n）/［（m＋n）（m－n）］｝［mn/（n－1）］＝［1/

再答：这个化简一下答案就有了。。。再问：不对你只算了个2m....的值前面还有个条件再答：式子开括号化简完不是m+n-3mn么？那把题目条件带入不就是答案了？再问：我看错了再答：好吧。。。

（2m-n）分之m

2mn/(4m^2-9)(2m-3)/(2m+3)分子分母同时乘(2m-3)=(2m-3)(2m-3)/(2m+3)(2m-3)=(4m^2-12m+9)/(4m^-9)

根据题意绝对值和完全平方非负所以mn-1=0m-n-2=0mn=1m-n=2（-2mn+2m+3n)-(3mn+2n-2m)-(m+4n+mn)=-2mn+2m+3n-3mn-2n+2m-m-4n-m

3/(2M-N)=3(2M-N)/(2M-N)²2MN/(4M²-4MN+N²)=2MN/(2M-N)²如果不懂,请Hi我,祝学习愉快!

2mn分之4m方—9=n分之2—9=n分之(2-9n)2m—3分之2m+3=3分之(6m-2m-3)=3分之(4m-3)再问：额不好意思啊我不小心手滑打错了应该是2mn分之4m方—9与2m—3分之2m

①2mn/4m^2-9=2mn/[(2m+3)(2m-3)]②2m-3/2m+3=(2m-3)(2m-3)/[(2m+3)(2m-3)]=(2m-3)²/[(2m+3)(2m-3)]③2mn

3(m^2n+mn)-4(mn-2m^2n)+mn.=3m^2n+3mn-4mn+8m^2n+mn.=11m^2n.

m^2/9+2mn/3+n^2=(1/9)(m^2+6mn+9n^2)=(1/9)(m+3n)^2a^2-14ab+49b^2=(a-7b)^216a^4+24a^2b^2+9b^4=(4a^2+3b