Question

Find the sum of the given ap 20 ,13,6, −1,…..18 terms
pls give the right answer
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Answer 1

Answer:

a=20

d= -7

n=18

put the values in the formula and you will get answer

n/2[2a + (n – 1)d]

Step-by-step explanation:

this formula is used to find sum of terms of ap for a given value of n...which is number of terms

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Answer 2

Answer:

711

Step-by-step explanation:

given : ap:20,13,6,-1

a=20

d=13-20=-7

n=18

sn=?

formula

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

sn=18/2[2(20)+(18-1)-7]

sn=9[40+19*-7]

sn=9[40-119]

sn=9[79]

sn=711