Question

Find the sum to n term of an ap 5 2 -1 -4 -7

Answer 1

Step-by-step explanation:

Given A.P is

5,2,−1,−4,−7,...…..

number of terms of A.P is n

first term of this A.P is A1 = 5

second term of this ap a2 = 2

common difference (d) = a2-a1 = -3

we know that sum of n term of an A.P is given by

Sn = n/2 [ 2a + (n-1) d]

= n/2 [ 2×5 + (n-1) × -3]

= n/2 [ 10 -3n +3 ]

hence the sum of n terms of given A.P is .

Sn = n/2 [ 10-3n+3]

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Answer 2

given a p is equal to 5,2, - 1 ,- 4, - 7

a=5

d 2 - 5=-3

n term A + (n-1) d

SN = 12[2a+(n-1)d)

n12 [2(5)+(n-1)(-3)]

n/2[10-3n+3]

13n-3n^2/2