Question

द फर्स्ट टर्म ऑफ एन ए पी एस फाइव एंड द कॉमन डिफरेंस इस फॉर कंपलीट द फॉलोइंग एक्टिविटी टू फाइंड द सम ऑफ फर्स्ट 12 terms of the art​

Answer 1

Question :

• The first term of an AP is 5 and the common difference is 4 . Complete the following activity to find the sum of first 12 terms .

Answer :

• 324

Given :

• a = 5
• d = 4
• n = 12

Solution:

The formula for sum of n terms of an AP is given by :

$\tt S_n = \dfrac{n}{2} [2a + (n - 1) d]$

$\therefore$ , the sum of first 12 terms of AP is :

$\tt S_{12} = \dfrac{12}{2} [2 \times 5 + ( 12- 1) 4]$

= 6 [ 10 + 11 × 4]

= 6 [ 10 + 44]

= 6 [ 54]

= 324

___________________________

AP stands for arithmetic progression and is a series that has a common difference x between its consecutive terms .

AP : a , a + d , a + 2d , a + 3d ........

The common equation for AP is :

$\tt a_n = a + (n -1)d$

where

• $\tt a_n = n^{th}$ term of the AP
• a = first term of AP
• n = the number of term
• d = common difference