Question

in an ap if a= - 5 l= 21 and s=200 then n is equal to

Answer 1

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In an ap if a= - 5 l= 21 and s=200 then n is equal to

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

$200 = \frac{n( - 5 + 21)}{2}$

$200 = - \frac{16n}{2}$

$200 = - 8n$

$n = - \frac{200}{8} = - \frac{100}{4} = - 25$

n=-25

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Answer 2

QUESTION:

• in an ap if a= - 5 l= 21 and s=200 then n is equal to

TO FIND:

• the 'n' th term

SOLUTION:

• a = -5, l = 21, s= 200

• Sn = n (a+l)

2

• 200 = n (-5 +21)

2

• 200 * 2 = 16n

• 400 = 16n

• n = 25

n is therefore 25