Answer:
14n^2.
Step-by-step explanation:
This is Arithmetic with first term a = 14 and common difference d = 28.
Sum of n terms = n/2[2a + (n-1)d]
= n/2(28 +( n -1)28]
= n/2(28 + 28n - 28)
= 14n^2
Answer:
14n²
Step-by-step explanation:
14 = 14 *1
42 = 14 *3
70 = 14 *5
28n -14 = 14*2n - 14 = 14*(2n -1)
14 + 42 + 70 + ........+(28n -14) = 14*1 + 14*3 + 14*5 + ....... + 14*(2n - 1)
= 14 * (1 + 3 + 5 + ......+ (2n-1) )
= 14 * n²
= 14n²
1 + 3 + 5 + .... +(2n -1) -> sum of first 'n' odd numbers.
Formula for finding sum of first 'n' odd numbers = n²
