Question

va rog multtttt!!!!!!!!​

Answer 1

$\frac{1}{3 \times 49} + \frac{1}{7 \times 9} + \frac{1}{ {21}^{2} }$

$\frac{1}{147} + \frac{1}{63} + \frac{1}{ {21}^{2} }$

$\frac{10}{441} + \frac{1}{ {21}^{2} }$

$\frac{10}{441} + \frac{1}{441}$

$\frac{11}{441}$