Question

the sum of first 10 terms od A.P -5,-2,-1,.. is ____.
A. 85
B. 82
C. 79
D. 76 ​

Answer 1

Answer:

The correct answer is Option(A) 85

Step-by-step explanation:

Given Arithmetic Progression is  is  -5,-2,-1,.......

To find,

The sum of the first 10 terms of the Arithmetic Progression

Recall the formula

The sum of the first 'n' terms of an Arithmetic Progression is

Sₙ = $\frac{n}{2} [2a+(n-1)d]$, where 'a' is the 1st term, d is the common difference of the Arithmetic Progression

Solution:

Here, the AP is -5,-2,-1,.......

The 1st term of the Arithmetic Progression =a =  -5

Common difference = d = a₂- a₁ = -2-(-5) = 3

n = 10

Substituting the values in Sₙ = $\frac{n}{2} [2a+(n-1)d]$,  we get

$S_{10} = \frac{10}{2} [2X-5 +(10-1)3]$

= 5((-10) + 27)

= 5×17

= 85

The Sum of the first 10 terms of the AP = 85

Hence the correct answer is Option(A)

#SPJ3

Answer 2

Answer:

79

Step-by-step explanation: