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koli123able
Group Title
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
 one year ago
 one year ago
koli123able Group Title
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
 one year ago
 one year ago

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sauravshakya Group TitleBest ResponseYou've already chosen the best response.1
1,1.4,1.8,.... This is in AP with first term 1 and common difference 0.4
 one year ago

sauravshakya Group TitleBest ResponseYou've already chosen the best response.1
Use sum formula of AP
 one year ago

amoodarya Group TitleBest ResponseYou've already chosen the best response.0
14/2(a1+a14)=n/2(5.6+5.6+(n1)*0.2)
 one year ago

amoodarya Group TitleBest ResponseYou've already chosen the best response.0
14/2(1+1+13(.4))=n/2(5.6+5.6+(n1)*0.2)
 one year ago

koli123able Group TitleBest ResponseYou've already chosen the best response.0
i did the first A.P and its coming 50.4
 one year ago

sauravshakya Group TitleBest ResponseYou've already chosen the best response.1
S14 =14/2 {2*1 + (141)0.4} = 50.4
 one year ago

koli123able Group TitleBest ResponseYou've already chosen the best response.0
i am stuck here
 one year ago

sauravshakya Group TitleBest ResponseYou've already chosen the best response.1
5.6,5.8,6.0,.... This is in AP with common difference 0.2 andfirt term 5.6
 one year ago

koli123able Group TitleBest ResponseYou've already chosen the best response.0
\[50.4=\frac{ n }{ 2 }[(2*5.6)+(n1)*0.2]\]
 one year ago

koli123able Group TitleBest ResponseYou've already chosen the best response.0
stuck here
 one year ago

sauravshakya Group TitleBest ResponseYou've already chosen the best response.1
Sn=50.4 n/2 { 2*5.6 + (n1)0.2}=50.4 n{11  0.2n}=100.8
 one year ago

koli123able Group TitleBest ResponseYou've already chosen the best response.0
2*5.6 its 11.2
 one year ago

sauravshakya Group TitleBest ResponseYou've already chosen the best response.1
11n 0.2n^2 =100.8 11n 2/10 n^2 =100.8 110n 2n^2 =1008
 one year ago

sauravshakya Group TitleBest ResponseYou've already chosen the best response.1
11.20.2=11
 one year ago

sauravshakya Group TitleBest ResponseYou've already chosen the best response.1
110n 2n^2 =1008 2n^2110n+1008=0 n^255n+504=0
 one year ago

koli123able Group TitleBest ResponseYou've already chosen the best response.0
how did became 110n 2n^2 =1008
 one year ago

sauravshakya Group TitleBest ResponseYou've already chosen the best response.1
dw:1359028396466:dw
 one year ago

sauravshakya Group TitleBest ResponseYou've already chosen the best response.1
Now,n^255n+504=0 CAN u solve for n
 one year ago

koli123able Group TitleBest ResponseYou've already chosen the best response.0
n= 11.61 and n= 43.38
 one year ago

koli123able Group TitleBest ResponseYou've already chosen the best response.0
now what?
 one year ago

koli123able Group TitleBest ResponseYou've already chosen the best response.0
The Answer should come n=8...i checked the answers
 one year ago

sauravshakya Group TitleBest ResponseYou've already chosen the best response.1
n=8 is surely not the correct solution
 one year ago

koli123able Group TitleBest ResponseYou've already chosen the best response.0
the book says that answer is n=8
 one year ago

koli123able Group TitleBest ResponseYou've already chosen the best response.0
how will it come 8
 one year ago

sauravshakya Group TitleBest ResponseYou've already chosen the best response.1
Sorry I did a algebra mistake
 one year ago

sauravshakya Group TitleBest ResponseYou've already chosen the best response.1
n=8 is correct
 one year ago

koli123able Group TitleBest ResponseYou've already chosen the best response.0
how????? plz plz tell me
 one year ago

sauravshakya Group TitleBest ResponseYou've already chosen the best response.1
Sn=50.4 n/2 { 2*5.6 + (n1)0.2}=50.4 n/2 {11+0.2n}=50.4 n{11+0.2n}=100.8 11n+0,2n^2=100.8 11n +2/10 n^2 =100.8 110n+2n^2=1008 55n+n^2=504 n^2+55n504=0 n^2+(638)n504=0 n^2 +63n 8n504=0 n(n+63)8(n+63)=0 (n8)(n+63)=0
 one year ago

sauravshakya Group TitleBest ResponseYou've already chosen the best response.1
Now, either n8=0 n=8 OR n+63=0 n=63 BUT n cannot be negative So, n=8
 one year ago

sauravshakya Group TitleBest ResponseYou've already chosen the best response.1
got it?
 one year ago

koli123able Group TitleBest ResponseYou've already chosen the best response.0
thanks
 one year ago

sauravshakya Group TitleBest ResponseYou've already chosen the best response.1
welcome
 one year ago
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