Question

what is the sum of an Ap 33,31,29,...9​

Answer 1

Answer:

HERE IS YOUR ANSWER DEAR✌️

299

Step-by-step explanation:

a= 33

d= 31-33= -2

last tern a +( n-1)d = 9

33+ (n-1)-2= 9

-2n+2= -24

-2n = -26

n= 13

sum, Sn= 13/2(2*33+( 11- 1)-2)

13/2(66-20)

13/2*46

13*23

=299

HOPE IT HELPS YOU MARK IT BRAINLIEST PLEASE

Answer 2

SolutioN :-

• AP = 33,31,29,...9
• First term ( a ) = 33
• Last term ( Aₙ ) = 9
• Difference = - 2

Firstly we have to find number of terms

★ Aₙ = a + ( n - 1 ) d

→ 9 = 33 + ( n - 1 ) × ( - 2 )

→ 9 - 33 = ( n - 1 ) × ( - 2 )

→ - 24 = ( n - 1 ) × ( - 2 )

→ - 24 / - 2 = n - 1

→ n - 1 = 12

→ n = 12 + 1

→ n = 13

Now , Sum of given AP

★ Sₙ = n/2 ( a + Aₙ )

→ Sₙ = 13/2 ( 33 + 9 )

→ Sₙ = 13/2 × 42

→ Sₙ = 13 × 21

→ Sₙ = 273

∴ Sum of given AP is 273