Question

What is the sum of the first 11 terms of an arithmetic progression if the 4th term is 11 and the 7th term is -4?

A) -75 B) 55 C) 11 D) 100

Answer 1

Answer:

$100 \\ \\ \\ \\ 254$

Step-by-step explanation:

hope you

Answer 2

Answer:

given a₄ = 1, a₇ = -4

to find sum of 11 terms S₁₁ = ?

a + 3d = 11

a + 6d = -4

on solving , we get - 3d = 15

=> d = -5

=> a = 26

.

S11 = 11/2 [ 2×26 + 10(-5) ]

=> 11/2 [ 52 - 50 ]

=> 11/2 (2)

=> 11

option C

therefore sum of first 11 terms is 11