\(3a=3+\frac{1}{3}+\frac{1}{3^2}+...+\frac{1}{3^{2018}}\)
\(2a=3a-a=3-\frac{1}{3}-\frac{1}{3^{2019}}< 3\Rightarrow a< \frac{3}{2}\)
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cho A = 1/2 +1/3+...+1/70. so sanh A voi 3
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So sanh voi 0
2019 . (-1) . 2 . (-3) . (-9) . 2020 . (-11) . 59 . (-7)
cho A=(1/2^2-1).(1/3^2-1).(1/4^2-1).....(1/100^2-1). So sanh A voi 1/2
so sanh A= 1/2^2 + 1/ 3^2 +1/4^2+...+ 1/300^2 voi 3/4
cho A = (1/2^2-1)(1/3^2-1)(1/4^2-1)...(1/100^2-1). so sanh voi -1/2
A=(1/2^2-1) * (1/3^2-1) *...*(1/100^2-1) so sanh A voi 2
A=(1/2^2-1) * (1/3^2-1) *...*(1/100^2-1) so sanh A voi 1/2
Khong lam phep tinh hay so sanh:
a.[-1]*[-2]*[-3]*...*[-2009] voi 0
b.[-1]*[-2]*[-3]*...*[-10] voi 1*2*3*...*9*10
so sanh A voi 1 biet A= 2^2019-(2^2018+2^2017+...+2^1+2^0)