Question

Find the sum of first 22 terms in an AP 8,3,-2​

Answer 1

a=8

d=-5

n=22

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

=22/2(2*8+(22-1)-5)

=11(16-105)

=11(-89)

=-979

The sum of first 22 terms is - 979.

Answer 2

Answer:

$\huge{\pink{\boxed{\green{\sf{S22=-979}}}}}$

Step-by-step explanation:

$\huge{\pink{\boxed{\green{\underline{\red{\sf{SOLUTION-}}}}}}}$

${\orange{given}} \\ { \pink{ \boxed{ \green{a1 = 8}}}} \\ { \pink{ \boxed{ \green{d = a2 - a1 = 3 - 8 = - 5}}}} \\ { \pink{ \boxed{ \green{n = 22 \: terms}}}} \\ \\ { \blue{to \: find}} \\ { \purple{ \boxed{ \red{S22 = }}}}$

☆ According to the given question and information:

☆ We know the values that are required to find Sn:

☆ And we know the basic formula of Sn

$\to Sn = \frac{n}{2} (2a + (n - 1)d) \\ \to S22 = \frac{22}{2} (2 \times 8 + (22 - 1) \times - 5) \\ \to S22 = 11(16 + 21 \times - 5) \\ \to S22 = 11(16 - 105) \\ \to S22 = 11 \times - 89 \\ { \pink{ \boxed{ \green{ \therefore S22 = - 979}}}}$

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