a, gọi d là ƯCLN(2n+1, 5n+2 )
\(\Rightarrow\hept{\begin{cases}2n+1⋮d\\5n+2⋮d\end{cases}}\Rightarrow\hept{\begin{cases}5\left(2n+1\right)⋮d\\2\left(5n+2\right)⋮d\end{cases}}\Rightarrow\hept{\begin{cases}10n+5⋮d\\10+4⋮d\end{cases}}\)
\(\Rightarrow\left(10+5\right)-\left(10+4\right)⋮d\)
\(\Rightarrow10+5-10-4⋮d\)
\(\Rightarrow1⋮d\)
\(\Rightarrow d=\left\{-1;1\right\}\)
vậy...............
Tim cac so tu nhien n de cac phan so sau la phan so toi gian:
a)2n+3/4n+1 b) 3n+2/7n+1 c)2n+7/5n+2
Tìm n đẻ cac phan so sau toi gian
3n+2/7n+1
2n+7/5n+2
8n+193/4n+3
6n+99/3n+4
chung minh 5n+3/3n+2la phan so toi gian (n thuoc Z)
tim n thuoc N de cac ap so sau nguyen to cung nhau
a) 3n + 2va 7n+1
b) 2n+7 va 5n+2
Cho phan so: P = \(\frac{2n+7}{5n+2}\)(n thuoc Z)
a)Tim n thuoc z de P la phan so chua toi gian.
b)Tim n thuoc Z sao cho P la phan so toi gian.
CMR phan so 3n+2/5n+3 toi gian voi moi n thuoc N
Chung to rang :
a)(2n + 1) (2n+2) chia het cho 3 . Voi n thuoc so tu nhien
b)(5n+1) (5n+2) chia het cho 6. Voi n thuoc so tu nhien.
tim n de phan so 2n+7/5n+2 la phan so toi gian
chung to rang vs moi so tu nhien n , phan so n^3+2n/n^4+3n^2+1 la toi gian
