Question

The first and the last term of an AP are 17 and 350 respectively.If the common difference is 9,how many terms are there and what is their sum?

Answer 1

Hey mate!!!
an=350   ;     d=9     ;      a=17
an=a+(n-1)d
350=17+(n-1)9
350-17=(n-1)9
333/9=n-1
37=n-1
n=38
for the sum of 38 terms;
Sn=n/2(a+l)
    =38/2(17+350)
    =19(367)
     =6973



HOPE THIS WILL HELP U!!

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Answer 2

Hey there!

Given,

a = 17
l = 350
d = 9

$n = \frac{(l - a)}{d} + 1$

$\frac{(350 - 17)}{9} + 1$

$\frac{333}{9} + 1$

$n = 38$

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

$sn = \frac{38}{2} (17 + 350)$

19 × 367

$sn = 6973$

Hope it helps!