1/3+2/32+3/33+4/34+...+n/3n<3/4 tìm n biết(n thuộc n*,n>3
Tim x biet: x+1/1974+x+2/1973+x+3/1972=-3
tim x biết (x+1) /1974 + (x+2) / 1973 + (x+3) / 1972=-3
Bài 1: Tính: A=31+33+35+37+...+3111
B=32+34+36+...+3200
C=51+53+55+...+599
D= 52+54+56+...+5100
Bài 2: Chứng minh các phân số sau tối giản với n ϵ N
a) \(\dfrac{2n+1}{n+1}\) b)\(\dfrac{2n+3}{3n+4}\)
Tìm x thuộc Q, biết:
a) (x-4).(x+1/3)>0
b) x+1/1974 + x+2/1973 + x+3/1974 = -3
Chứng minh rằng:
A = 1/3 + 1/32 + 1/33 + ..........+ 1/399 < 1/2
B = 3/12x 22 + 5/22 x 32 + 7/32 x 42 +............+ 19/92 x 102 < 1
C = 1/3 + 2/32 + 3/33 + 4/34 +.........+ 100/3100 ≤ 0
\(\frac{x+1}{1974}+\frac{x+2}{1973}+\frac{x+3}{1972}=-3\)
\(\frac{x+5}{2005}+\frac{x+6}{2004}+\frac{x+7}{2003}=-3\)
TÌM X
Bài 2
a) \(A=\left(\frac{1}{2}-1\right)\left(\frac{1}{3}-1\right)...\left(\frac{1}{2002}-1\right)\left(\frac{1}{2003}-1\right)\)
b) \(B=\left(-1\frac{1}{2^2}\right)\left(-1\frac{1}{3^2}\right)\left(-1\frac{1}{4^2}\right)...\left(-1\frac{1}{2003^2}\right)\left(-1\frac{1}{2004^2}\right)\)
c) \(C=\left(1-\frac{1}{2^2}\right)\left(1-\frac{1}{3^2}\right)\left(1-\frac{1}{4^2}\right)...\left(1-\frac{1}{n^2}\right)\left(n\in N,n\ge2\right)\)
Tìm x, biết\(\frac{x+1}{1974}+\frac{x+2}{1973}+\frac{x+3}{1972}=-3\)