Question

Find the sum of 2,7,12.... to 10 terms​

Answer 1

AP : 2, 7, 12, .... to 10 term

Here ..

First term (a) = 2

Common difference (d) = $a_{2}$ - $a_{2}$

= 7 - 2 = 5

Number of terms (n) = 10

______________ [GIVEN]

• We have to find $S_{10}$

____________________________

* $S_{n}$ = $\dfrac{10}{2}$ [2a + (n - 1)d]

Put the known values in above equation

$\implies$ $S_{10}$ = $\dfrac{n}{2}$ [2 (2) + (10 - 1)5]

$\implies$ 5 [4 + 9(5)]

$\implies$ 5 (4 + 45)

$\implies$ 5 × 49

____________________________

$S_{10}$ = 249

___________ [ANSWER]