Đáp án:
`(\frac{1}{1.2} + \frac{1}{2.3} + \frac{1}{3.4} + ... + \frac{1}{99.100}) × x = \frac{33}{100}`
`(1 - \frac{1}{2} + \frac{1}{2} - \frac{1}{3} + \frac{1}{3} - \frac{1}{4} + ... + \frac{1}{99} - \frac{1}{100}) × x = \frac{33}{100}`
`(1 - \frac{1}{100}) × x = frac{33}{100}`
`\frac{99}{100} × x = \frac{33}{100}`
`x = \frac{33}{100} : \frac{99}{100}`
`x = \frac{1}{3}`
Vậy `x = \frac{1}{3}`.
Chúc học tốt!!!
