Math, asked by cpshukla96, 10 months ago

What is the sum of first 17terms if the first term is -20 and last term is 28 in an AP

Answers

Answered by madhutiwari793

Answer:

Step-by-step explanation:

sum of n terms = n/2 (a+l)

where

n=17

a= -20

l= 28

sum of first 17 terms = 17×8/2

= 17*4

please mark BRAINIEST

Answered by brainlyaryan12

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$S_n=\frac{n}{2}(a+l)$

n = the term to where the sum is to be taken

a = first term

l = last term

=> $S_{17}=\frac{17}{2}(-20+28)$

=> $S_{17}=\frac{17}{2}×8$

=> $S_{17}=17×4$

$\huge\orange{\fbox{\pink{S_{17}=68}}}$

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