Question

In an ap it is given that common difference is 5 and sum of its first ten terms is 75.find the first term of the ap

Answer 1

Step-by-step explanation:

d= 5

S10= 75

n/2 [2a + (n-1)d] = 75

10/2 [2a + (10-1)(5)] = 75

5 [2a + (9)(5)] = 75

[2a + 45] = 15

2a = -30

a = -15

Answer 2

-15

step by step explanation in this pic