a) 1³ + 2³ + 3³ + 4³ + 5³

= 1 + 8 + 27 + 64 + 125

= 9 + 27 + 64 + 125

= 36 + 64 + 125

= 100 + 125

= 225 

<=> 225 = 15²

b) 1³ + 2³ + 3³ + 4³ + 5³ + 6³

= 1 + 8 + 27 + 64 + 125 + 216

= 9 + 27 + 64 + 125 + 216

= 36 + 64 + 125 + 216

= 100 + 125 + 216

= 225 + 216

= 441

<=> 441 = 21²

a) 15²

b) 21²

\(2009A=\frac{2009^{2010}+2009}{2009^{2010}+1}=\)\(\frac{2009^{2010}+1+2008}{2009^{2010}+1}=1+\frac{2008}{2009^{2010}+1}\)

\(2009B=\frac{2009^{2009}+2009}{2009^{2009}+1}=\frac{2009^{2009}+1+2008}{2009^{2009}+1}\)\(=1+\frac{2008}{2009^{2009}+1}\)

Vì \(1+\frac{2008}{2009^{2010}+1}< 1+\frac{2008}{2009^{2009}+1}\) \(\Leftrightarrow A< B\)

\(A=\frac{2009^{2009}+1}{2009^{2010}+1}\Rightarrow2009A=\frac{2009^{2010}+2009}{2009^{2010}+1}\)

\(2009A=\frac{2009^{2010}+1}{2009^{2010}+1}+\frac{2008}{2009^{2010}+1}\)

\(2009A=1+\frac{2008}{2009^{2010}+1}\)

..... sory bn mk hơi luwoif chút nên bn tự lm tương tự vs phần B và so sánh nhé!^^

B={4;6;9;11}

B={4;6;9;11}

Đó là tháng 5,6,7

Quý 2 có tháng 5,6,7

Đặt :

\(A=\frac{2^{2014}+1}{2^{2014}}=\frac{2^{2014}}{2^{2014}}+\frac{1}{2^{2014}}=1+\frac{1}{2^{2014}}\)

\(B=\frac{2^{2014}+2}{2^{2014}+1}=\frac{2^{2014}+1+1}{2^{2014}+1}=\frac{2^{2014}+1}{2^{2014}+1}\)\(=1+\frac{1}{2^{2014}+1}\)

\(1+\frac{1}{2^{2014}}>1+\frac{1}{2^{2014}+2}\Leftrightarrow A>B\)

=> x-1 \(\in\) Ư(13) = { 1,13,-1,-13 }

Ta có bảng :

Vậy các số nguyên x là -12,2,14

13/x-1 la so nguyen thi 13 chia het cho x-1

suy ra x-1 thuoc uoc cua 13

ma UOC CUA 13 LA 13;1;-1;-13

khi x-1=13 thi x=14

khi x-1=1 thi x=2 

khi x-1 =-1 thi x=0

khi x-1 =-13 thi x=-12

vay cac so nguyen x la 14;2;0;-12

3240 = 3000 + 200 + 40 + 0

3240=3000+200+40