先化简在求值,(m-n)²-m(m-2n),其中m=根号3,n=根号2-搜答案-智慧作业帮

原式=4m²-n²+2mn+n²-4m²=2mn=2×(-1/2)×2013=-2013

(m²+n²+mn)/(m²-n²)分子分母同除以n²=[(m/n)²+1+m/n]/[(m/n)²-1]=[(7/8)²

原式可化为,m（n+2）-2mn+n(m+2)=2(m+n),条件可化为m2-n2=n+2-m-2=（m-n)(m+n)【m不等于n}得m+n=-1,所以原式等于-2应该整体代换m=n=2时答案是8m

m/(m-n)-n/(m+n)+2mn/(m²-n²)=[m(m+n)-n(m-n)+2mn]/(m²-n²)=(m²+n²)/(m

8m^2-(6m^2+15m^2n)÷3m+m(n-1)=8m^2-2m-5mn+mn-m=8m^2-4mn-3m代入m=2,n=1得出原式=8*2^2-4*2*1-3*2=32-8-6=18

(m+n)(m一n)一(一2m+3n)(一2m一3n),=(m+n)(m一n)一(2m-3n)(2m+3n),=m^2-n^2-(4m^2-9n^2)=8n^2-3m^2(m=1,n=一1)=8-3=

-2（mn-3m^2）-m^2+5（mn-m^2）+2mn=-2mn+6m^2-m^2+5mn-5m^2+2mn=5mn当m=1,n=-2时原式=5×1×（-2）=-10再问：谢谢。你是个好人啊

(2m-m^2n)/(m^2n^2-4).=[m(2-mn)]/[(mn+2)(mn-2)]=-m/(mn+2)=-2/(-4)=1/2

m^2-n^2/2m-2n=(m+n)(m-n)/2(m-n)=(m+n)/2=(7-3)/2=2

（2m-n）分之m

(5m-2m)+(3n-8n)=3m-6n=0.8

5（m+n）（m-n）-2（m+n）2-3（m-n）2=5（m2-n2）-2（m2+2mn+n2）-3（m2-2nm+n2）=5m2-5n2-2m2-4mn-2n2-3m2+6nm-3n2=-10n2

8m(m+n)²-2m(m-n)²=2m(4(m+n)²-(m-n)²)=2m(2m+2n+m-n)(2m+2n-m+n)=2m(3m+n)(3n+m)再把m=

=m^2-n^2+m^2+2mn+n^2-2m^2=2mn=2*3*(-1)=-6再问：因式分a的3次方-3a的2次方-10a再答：=a(a^2-3a-10)=a(a-5)(a+2)

=(m^2-n^2)(-m^2-n^2)-(4m^2-n^2)(4m^2+n^2)=-(m^4-n^4)-(16m^4-n^4)=-（1^4-（-2)^4）-(16*1^4-(-2)^4)=15

我怀疑你少一个平方m/(m+3)-6/(m-9)÷2/(m-3)=m/(m+3)-6/(m+3)(m-3)×(m-3)/2=m/(m+3)-3/(m+3)=(m-3)/(m+3)当m=-2时原式=(-

8m2-5m（-m+3n）+4m（-4m-52n）=8m2+5m2-15mn-16m2-10mn=-3m2-25mn，当m=2，n=-1时，原式=-3×22-25×2×（-1）=38．

原式=4m²-n²+mn+2n²-4m²-4mn-n²=-3mn

[(3m-n)^2-(3m-n)(3m+n)-4mn]/(2n)=[（9m²+n²-6mn）-（9m²-n²）]/(2n)=(9m²+n²-

(2m+n)(2m-n)+n(2m+n)-8m²n²÷(2n)m=-1/24m²-n²+2mn+n²-4mn=-1/28m²-4mn=-1