Question

3) Find the sum of the first 50 terms. *
8 + 20+32 +44 + ...

Answer 1

• 15100

Step-by-step explanation :

Sum of first 50 terms for the AP:

`\dashrightarrow { \boxed{\sf S = (n)/(2) (2a + (n - 1)d )}}`

where ,

• Total no. of terms (n)= 50
• Comman difference (d) = 20 - 8 = 12
• First term (a) = 8

On substituting the values , we get :

`\dashrightarrow \sf S = (50)/(2)(2 * 8 + (50 - 1) * 12) \ \\ \\ \dashrightarrow \sf S = 25(16 + 49 * 12 ) \\ \\ \dashrightarrow \sf S = 25(16 + 588 )\\ \\ \dashrightarrow \sf S = 25(604 )\\ \\ \dashrightarrow \sf S = 15100 \\`

`\therefore` Sum of the first 50 terms is 15100