Question

the first and the last term of an Ap are 17 and 350 . if comman difference is 9 , how many terms are there and what is there sum

Answer 1

Answer:

FINDING NUMBER OF TERMS:

a=17

an=350

d=9

an=a+(n-1)d

350=17+(n-1)9

350-17=(n-1)9

333/9=n-1

37=n-1

37+1=n

38=n

SO IN THIS AP THERE ARE 38 TERMS

FINDING SUM IF 38 TERMS

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

S38=38/2(2(17)+(38-1)9)

=19(34+37*9)

=19(34+333)

=19(367)

=6973

AND THEIR SUM IS 6973

HOPE IT HELPS

MARK AS BRAINLIEST

Answer 2

Answer :- a = 38 , s = 6973

Explanation :- a = 17 , an = 350 , d = 9 .

Formula used :- an= a+(n-1)×d

350 = 17 +( n - 1) × 9

350 - 17 = (n-1) × 9

$\dfrac{333}{9}$ = (n-1)

37 + 1 = n

38 = n ✓

2nd formula = s = $\dfrac{n}{2}$ [2a + (n - 1) ×d ]

s = $\dfrac{38}{2}$ [2×17 +(38-1) 9 ]

s = 19 [34+37×9]

s = 19 [367]

s = 6973 . ✓

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