Question

The sum of first 10 terms of A.P. -2 , -2.5, -3 …………is

Answer 1

here is your answer, mate

Answer 2

$\huge{\blue{SOLUTION-}}$

GIVEN-

a = -2

d = -2.5 -(-2) = -0.5

n = 10

TO FIND

Sum of first 10 terms

ANSWER

As we know,

$\boxed{S_{n}={\frac{n}{2}2a+(n-1)d}}$

Using this formula we get,

${S_{10}}$ = $\frac{10}{2}$ 2(-2) + 9(-0.5)

${S_{10}}$ = 5 (-4-4.5)

${S_{10}}$ = 5 {- 8.5}

${S_{10}}$ = -42.5