Question

a)
If 10th term of an A.P is 13, then the sum of 19 terms
a) 26
b) 247
c) 352​

Answer 1

Answer:

247

Step-by-step explanation:

$a10 = 13 \\ a + 9d = 13 - - - - - - - eq(1) \\ s19 = \frac{19}{2} (2a + 18d) \\ \div \: by \: 2 \\ = 19(a + 9d) \\ = 19(13) - - - - by \: \: eq(1) \\ s19 = 247$