Question

There are total $$9$$ terms in an A.P. If the last term and the sum of all the terms are $$28$$ and $$144$$ respectively, then the first term is ______.

Options

• $$1$$

• $$7$$

• $$4$$

• $$5$$

Answer 1

There are total $$9$$ terms in an A.P. If the last term and the sum of all the terms are $$28$$ and $$144$$ respectively, then the first term is 4.

Explanation:

$$144 = \frac{9}{2}(a + 28)$$ gives $$a + 28 = 32$$, so $$a = 4$$.