chứng minh rằng 2/3^2+3/3^3+4/3^4+............+2016/3^2016
Cho S=1/4+2/4^2+3/4^3+...+2016/4^2016. Chứng minh rằng S<1/2
Chứng minh rằng A=\(\left(4+4^2+4^3+...+4^{2016}\right)⋮21;420\)
A=\(\left(2016+2016^2+2016^3+...+2016^{2016}\right)⋮2017\)
Chứng minh rằng
\(\frac{2}{3^2}+\frac{3}{3^3}+\frac{4}{3^4}+...+\frac{2016}{3^{2016}}< \frac{5}{12}\)
Chứng minh rằng:
\(\frac{2}{3^3}+\frac{3}{3^3}+\frac{4}{3^4}+...+\frac{2016}{3^{2016}}< \frac{5}{12}\)
Chứng minh rằng:
A=3^1+3^2+3^3+3^4+......3^2016:4
A=3+32+33+34+...+32016
A=(3+32)+(33+34)+...+(32015+32016)
A=3.(1+3)+33.(1+3)+...+32015.(1+3)
A=3.4+33.4+...+32015.4
A=4.(3+33+...+32015) chia hết cho 4 (đpcm)
chứng minh rằng:1/2! + 2/3! + 3/4! + ..... + 2016/2017!
Chứng minh rằng A = 3+3^2+3^3+3^4+...+3^2016 chia hết cho 40
A=3+32+.........+32016
A=3.(1+3+9+27)+.....+32013.(1+3+9+27)
A=3.40+.....+32013.40
A=40.(3+...+32013)
=> A\(⋮40\)
=> ĐPCM .
Chứng minh rằng: a/M= 1/3-1/3^2+1/3^3-1/3^4+1/3^5-1/3^6<1/4
b/N=1/3-2/3^2+3/3^3-4/3^4+...+2015/3^2015-2016/3^2016<3/16
chứng tỏ rằng:
1/4<1/5+2/5^2+3/5^3+...+2016/5^2016<1/3