Question

if the sum of first 8 terms of Ap is 180 find the sum of first and last terms​

Answer 1

Answer:

$\large{\underline{\boxed{\sf 45}}}$

Step-by-step explanation:

Given that ;

Sum of 8 terms of an A.P is 180.

• S₈ = 180

We need to find the sum of first and last terms, i.e., (a + l).

As we know that -

$\rm S_n = \frac{n}{2}[a + l] \\ \\ \implies \rm S_8 = 180 \\ \\ \implies \rm \frac{8}{2}[a + l] = 180 \\ \\ \implies \rm 4[a + l] =180 \\ \\ \implies \rm [a + l] = \frac{180}{4} \\ \\ \implies \rm [a + l] =45$

Hence, the sum of first and last term of the given AP is 45.

Answer 2

GIVEN:

Sum of the first 8 terms of an AP = 180

We know that,

Sum of terms in an AP, Sn = n/2 [ a + an ]

180 = n/2 [ a + an ]

180 = 8/2 [ a + an ]

180 = 4 [ a + an ]

a + an = 180/4

a + an = 45

Therefore, the sum of the first and last term is 45.