Question

the sum of 10 terms of AP 2,7,12 is a) 345 b) 245 c) 500 d) 200​

Answer 1

Correct answer is option b)245

Step-by-step explanation:

Correct option is

B

245

Clearly, the given sequence is an AP with first term a=2, common difference d=5 and n=10.

Now,

S10= 2/10 [2a+(10−1)d]

=5[2×2+9×5]

=245

Answer 2

Answer:

2,7,12 is AP

d = a2 - a1 = 7-2 = 5

find sum of 10 terms

therefore n= 10

Sn =

$\frac{n}{2} \times (2a + (n - 1)d) \\ \frac{10}{2} \times (2 \times 2 + (10 - 1)5) \\ 5 \times (4 + 45) \\ 5 \times 49 \\ 245$