Question

Find the sum of first 22 terms of the AP: 8, 3, -2, .....

• A. -899
• B. -1010
• C. -979
• D. -880

Answer 1

Answer:

C. -979

$a=8,d=3-8=-5,n=22$

$S_n=n/2(2a+(n-1)d)$

$S_{22}=22/2\times(2\times8+(22-1)\times-5$

$=11(16+21\times-5$

$=11\times-89$

$=-979$