choA=3^2018-3^2017+3^2016-......-3^3+3^2-3+1
a)rút gọn A
b) tìm chữ số tận cùng của 4*A
choA=2 mũ 0 +2 mũ 1+...+ 2 mũ 2018
B=2 mũ 2019-1
chứng minh rằng A=B
A=1/2 +1/2^2+1/2^3+......+1/2^2018
cmr A<1
CHOA=1.2.3+2.3.5+3.4.7+...=n.(n+1).(2.n+1)
CMR A=n.(n+1)^2.(n+2):2
cmr n=1/4^2+1/6^2+1/8^2+...+1/2018^2<1
p= 2!/3!+2!/4!+2!/5!+.+2!/99<1
1) CMR:
\(\frac{1}{3^2}+\frac{1}{4^2}+\frac{1}{5^2}+\frac{1}{6^2}+...+\frac{1}{100^2}< \frac{1}{2}\)Ai nhanh mk tick
2) So sánh 2 số:
\(A=\frac{5^{2018}-2016}{5^{2018}-2017}\)\(Với\)\(B=\frac{5^{2018}-2018}{5^{2018}-2019}\)
cho S=\(\frac{1}{4}+\frac{2}{4^2}+\frac{3}{4^3}+...+\frac{2018}{4^{2018}}\)CMR: S<\(\frac{1}{2}\)
ChoA=1/1^2+1/2^2+1/3^2+1/4^2+...+1/50^2
Chung minh A <2
Bài 1
ChoA=1+42+44+...+42018
Tìm x biết:
15A = 23x-1-1
