Question

The sum of first 14 terms of 1,1.4,1.8,.... is equal to the sum of first n terms of 5.6,5.8,6.0,.... , find the value of n

Answer 1

1,1.4,1.8,....
This is in AP with first term 1 and common difference 0.4

Answer 2

Use sum formula of AP

Answer 3

14/2(a1+a14)=n/2(5.6+5.6+(n-1)*0.2)

Answer 4

14/2(1+1+13(.4))=n/2(5.6+5.6+(n-1)*0.2)

Answer 5

i did the first A.P and its coming 50.4

Answer 6

S14 =14/2 {2*1 + (14-1)0.4} = 50.4

Answer 7

i am stuck here

Answer 8

5.6,5.8,6.0,....
This is in AP with common difference 0.2 andfirt term 5.6

Answer 9

\[50.4=\frac{ n }{ 2 }[(2*5.6)+(n-1)*0.2]\]

Answer 10

stuck here

Answer 11

Sn=50.4
n/2 { 2*5.6 + (n-1)0.2}=50.4
n{11 - 0.2n}=100.8

Answer 12

2*5.6 its 11.2

Answer 13

11n -0.2n^2 =100.8
11n -2/10 n^2 =100.8
110n -2n^2 =1008

Answer 14

11.2-0.2=11

Answer 15

oh

Answer 16

110n -2n^2 =1008
2n^2-110n+1008=0
n^2-55n+504=0

Answer 17

how did became 110n -2n^2 =1008