Question

find the sum
34+32+30........................ +10

Answer 1

a = 34

cd = -2

10 = 34 + ( n - 1 ) * -2

- 24 / -2 = ( n - 1 )

13 = n

Sn = 13 / 2 * 44 = 13 * 22 = 286 Ans.

Answer 2

Answer:

286

Step-by-step explanation:

Given, Series is 34 + 32 + 30 + ... + 10.

Clearly this series is in A.P.

First term = 34.

Common difference = -2

Last term = 10.

Let n be the number of terms.

an = 10

⇒ a + (n - 1) * d = 10

⇒ 34 + (n - 1) * (-2) = 10

⇒ 34 - 2n + 2 = 10

⇒ n = 13

∴ Sum = (n/2)[a + l]

          = (13/2)[34 + 10]

          = 13[22]

          = 286.

Therefore, Sum is 286.

Hope it helps!