设m 等于4XX-8XX-2,N等于
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1*2+2*3+...+(n-1)*n=(1^2-1)+(2^2-2)+(3^2-3)+……+(n^2-n)=(1^2+2^2+3^2+……+n^2)-(1+2+3+……+n)=n(n+1)(2n+1
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∵xx2+x+1=a(a≠0),x≠0,∴x2+x+1x=1a,即x+1x=1a-1,两边平方得:(x+1x)2=(1−aa)2,即x2+1x2+2=(1−a)2a2,整理得:x2+1x2=−a2−2
m²+n²=4mnm²+n²-2mn=4mn-2mn(m-n)²=2mn(m-n)²/mn原式=2mn/mn=2【中学生数理化】团队wdxf
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因为n是关于X的方程x²+mx+2n=0所以n²+mn+2n=0n(n+m+2)=0因为n≠0,所以n+m+2=0m+n=-2
/>原式=2n/(m+2n)-m/(m-2n)-4mn/(m²-4n²)=2n/(m+2n)-m/(m-2n)-4mn/(m²-4n²)=[2n(m-2n)-m
原式=SnX*Sn=1xX^2+2xX^3+…+nxX^(n+1)=Sn+1-(X+X^2+X^3+…+X^n+X^n+1)Sn+1-X*Sn=(X-X^n+2)/(1-X)Sn+1=Sn+(n+1)
xx+2xy-yy=-3两式相加即可
{1,5}={x|(x-1)(x-5)=0}{x|x^2+x-1=0}={x|x=(-1±√5)/2}{x|x∈N,1
(18+12)x÷2=12030x÷2=12030x=240x=8再问:大哥括号里面是加!再答:(18+12)x÷2=12030x÷2=12030x=240x=8
11.3X9.8——————9041017——————110.74
xx+yy+4x-6y+13=0整理得:(x+2)^2+(y-3)^2=0那么只有(x+2)=0(y-3)=0x=-2y=3(x^2-2x)/(x^2+3y^2)=(4+4)/(4+3*9)=8/31
m^2+n^2=4m则mn分之m^2-n^2=(m^2-n^2)/mn=(m+n)(m-n)/mn=√[(m+n)²(m-n)²]/mn=√[(m²+2mn+n²
原式=2n/(m+2n)-m/(m-2n)-4mn/(m²-4n²)=2n/(m+2n)-m/(m-2n)-4mn/(m²-4n²)=[2n(m-2n)-m(m
原式=(6m-1)xx+(4n+2)xy+2x+y+4前两项时二次项所以他们的系数为0所以6m-1=04n+2=0所以6m=1,2n=-1所以6m-2n+2=0+1+2=3
M=1*2+2*3+3*4+.+(n-1)*n=1*1+1+2*2+2+3*3+3+……+(N-1)*(N-1)+(N-1)=1²+2²+3²+……+(N-1)²