Question

sigma 10+ sigma 25. solve​

Answer 1

To find: $\sum 10+\sum 25$

Step-by-step explanation:

We know that, $\sum n=\dfrac{n(n+1)}{2}$

When $n=10$, we get

$\quad\sum 10=\dfrac{10(10+1)}{2}$

$\Rightarrow \sum 10=\dfrac{10\times 11}{2}$

$\Rightarrow \sum 10=55$

When $n=25$, we get

$\quad\sum 25=\dfrac{25(25+1)}{2}$

$\Rightarrow \sum 25=\dfrac{25\times 26}{2}$

$\Rightarrow \sum 25=325$

Therefore, $\sum 10+\sum 25$

$=55+325$

$=380$

Answer: $\sum 10+\sum 25=380$