Gọi d là ƯCLN ( 2n - 1 ; 2n - 2 )
=> 2n - 1 ⋮ d
=> 2n - 2 ⋮ d
=> [ ( 2n - 2 ) - ( 2n - 1 ) ] ⋮ d
=> 2 - 1 ⋮ d
=> 1 ⋮ d => d = 1
Vì ƯCLN ( 2n - 1 ; 2n - 2 ) = 1 nên 2n-1/2n-2 là phân số tối giản
Ccs câu sau làm tương tự
cac phan so \(\frac{n+1}{2n+3}\)va\(\frac{2n+1}{2n+3}\)la cac phan so toi gian voi moi so nguyen n khac -1
chung to phan so toi gian voi n thuoc n a , n+1/2n+3 b, 2n +3 /4n +8
Cau 1: Chung minh rang cac phan so sau la phan so toi gian voi moi so nguyen?
a, 8n + 5 phan 6n + 4 b, n + 1 phan 2n + 3 c, 2n + 3 phan 3n + 5
Cau 2: Tim tat ca cac so tu nhien n de phan so sau la toi gian
a, n + 13 phan n - 2. b, 18n + 3 phan 21n + 7
Ai giai day du va nhanh thi mk se tick cho
Chung to rang phan so
\(\frac{2n+3}{4n+8}\)
toi gian voi moi so tu nhien.
Chung minh rang phan so sau toi gian voi moi n thuoc N 2n+1/2n(n+1)
Chung minh rang moi phan so dang n+1/2n+3 ( n thuoc N ) deu la phan so toi gian.
Giup to bai nay voi : Chung minh voi n thuoc N sao phan so sau la phan so toi gian 4n+1/6n+1
Chung to rang cac phan so sau toi gian voi moi STN n
a)n+1/2n+3 b)2n+3/4n+8
Tim n de phan so sau toi gian voi n thuoc N 2n+3/4n+1
