a) So am

b) co nhieu nhat 22 so duong . vi ......

a, số âm 

b , có 22

a có thể = số khác mà.

VD: a=5 thì 5'2 chia hết cho 24 (đpcm)

Đề bài sai đúng mỗi trường hợp a=5 hoăc -5 thôi!!

x^2+1^2+y^2+1^2+x^2-y^2=2

x^2+1+x^2+1=2

2x^2=2-1-1

2x^2=0

x^2=0:2

x^2=0

Mà 0^2=0=>x=0

 \(A=\left(\frac{7}{9}+1\right)\left(\frac{7}{20}+1\right)\left(\frac{7}{33}+1\right)..........\left(\frac{7}{2900}+1\right)\)

 \(A=\frac{16}{9}.\frac{27}{20}.\frac{40}{33}.......\frac{2907}{2900}\)

 \(A=\frac{2.8}{1.9}.\frac{3.9}{2.10}.\frac{4.10}{3.11}......\frac{51.57}{50.58}\)

 \(A=\frac{2.3.4.....51}{1.2.3......50}.\frac{8.9.10.......57}{9.10.11........58}\)

 \(A=51.\frac{4}{29}\)

 \(A=\frac{204}{59}\)

Vậy \(A=\frac{204}{59}\)

\(A=\left(1+\frac{1}{2}+\frac{1}{3}+...+\frac{1}{98}\right).2.3.4..98\)

\(=\left(1+\frac{1}{2}+\frac{1}{3}+...+\frac{1}{98}\right).\left[2.\left(4.5.6...32\right)\left(34.35.36...98\right)\right].3.33\)

\(\left(1+\frac{1}{2}+\frac{1}{3}+...+\frac{1}{98}\right).\left[2.\left(4.5.6...32\right)\left(34.35.36...98\right)\right].99\)chia hết cho 99

A chia 99 dư 0

Ai làm được không?

easy but i don't know

\(p=\frac{1}{49}+\frac{2}{48}+\frac{3}{47}+\frac{4}{46}+...+\frac{48}{2}+\frac{49}{1}\)

\(p=\left(\frac{1}{49}+1\right)+\left(\frac{2}{48}+1\right)+\left(\frac{3}{47}+1\right)+\left(\frac{4}{46}+1\right)+...+\left(\frac{48}{2}+1\right)+1\)

(do ta tách số 49 thành tổng của 49 số 1, sau đó nhóm mỗi phân số trên với 1)

\(p=\left(\frac{1}{49}+\frac{49}{49}\right)+\left(\frac{2}{48}+\frac{48}{48}\right)+\left(\frac{3}{47}+\frac{47}{47}\right)+\left(\frac{4}{46}+\frac{46}{46}\right)+...+\left(\frac{48}{2}+\frac{2}{2}\right)+1\)

\(p=\frac{50}{49}+\frac{50}{48}+\frac{50}{47}+\frac{50}{46}+...+\frac{50}{2}+1\)

\(p=50.\left(\frac{1}{49}+\frac{1}{48}+\frac{1}{47}+\frac{1}{46}+...+\frac{1}{2}\right)+1=50.\left(\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{49}\right)+1=50.s+1\)=> p = 50.s + 1