Question

1/3^2+1/4^2+1/5^2+.....+1/97^2+1/98^2 So sánh A với 1/2

gúp tui vs nha thank!!!

Answer 1

Đặt \(A=\frac{1}{3^2}+\frac{1}{4^2}+\frac{1}{5^2}+....+\frac{1}{98^2}\)

Ta có : \(A< \frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{97.98}\)

\(A< \frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+....+\frac{1}{97}-\frac{1}{98}\)

\(A< \frac{1}{2}-\frac{1}{98}\)

\(A< \frac{1}{2}\)

GOOD LUCK !!!

Answer 2

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