Question

$\frac{1}{3\times5}+\frac{1}{5\times7}+......+\frac{1}{13\times15}=?$

• A. 5/45
• B. 6/45
• C. 7/45
• D. 8/45

Answer 1

Answer:

B. 6/45

$\frac{1}{3\times5}+\frac{1}{5\times7}+......+\frac{1}{13\times15}$

$= (\frac{1}{3}-\frac{1}{15})\times\frac12$

$= \frac{12}{45}\times\frac12$

$=\frac{6}{45}$