anonymous
  • anonymous
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
Mathematics
  • Stacey Warren - Expert brainly.com
Hey! We 've verified this expert answer for you, click below to unlock the details :)
SOLVED
At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat.
chestercat
  • chestercat
I got my questions answered at brainly.com in under 10 minutes. Go to brainly.com now for free help!
anonymous
  • anonymous
1,1.4,1.8,.... This is in AP with first term 1 and common difference 0.4
anonymous
  • anonymous
Use sum formula of AP
amoodarya
  • amoodarya
14/2(a1+a14)=n/2(5.6+5.6+(n-1)*0.2)

Looking for something else?

Not the answer you are looking for? Search for more explanations.

More answers

amoodarya
  • amoodarya
14/2(1+1+13(.4))=n/2(5.6+5.6+(n-1)*0.2)
anonymous
  • anonymous
i did the first A.P and its coming 50.4
anonymous
  • anonymous
S14 =14/2 {2*1 + (14-1)0.4} = 50.4
anonymous
  • anonymous
i am stuck here
anonymous
  • anonymous
5.6,5.8,6.0,.... This is in AP with common difference 0.2 andfirt term 5.6
anonymous
  • anonymous
\[50.4=\frac{ n }{ 2 }[(2*5.6)+(n-1)*0.2]\]
anonymous
  • anonymous
stuck here
anonymous
  • anonymous
Sn=50.4 n/2 { 2*5.6 + (n-1)0.2}=50.4 n{11 - 0.2n}=100.8
anonymous
  • anonymous
2*5.6 its 11.2
anonymous
  • anonymous
11n -0.2n^2 =100.8 11n -2/10 n^2 =100.8 110n -2n^2 =1008
anonymous
  • anonymous
11.2-0.2=11
anonymous
  • anonymous
oh
anonymous
  • anonymous
110n -2n^2 =1008 2n^2-110n+1008=0 n^2-55n+504=0
anonymous
  • anonymous
how did became 110n -2n^2 =1008
anonymous
  • anonymous
|dw:1359028396466:dw|
anonymous
  • anonymous
ok
anonymous
  • anonymous
Now,n^2-55n+504=0 CAN u solve for n
anonymous
  • anonymous
n= -11.61 and n= -43.38
anonymous
  • anonymous
now what?
anonymous
  • anonymous
The Answer should come n=8...i checked the answers
anonymous
  • anonymous
n=8 is surely not the correct solution
anonymous
  • anonymous
the book says that answer is n=8
anonymous
  • anonymous
how will it come 8
anonymous
  • anonymous
Sorry I did a algebra mistake
anonymous
  • anonymous
n=8 is correct
anonymous
  • anonymous
how????? plz plz tell me
anonymous
  • anonymous
Sn=50.4 n/2 { 2*5.6 + (n-1)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+55n-504=0 n^2+(63-8)n-504=0 n^2 +63n -8n-504=0 n(n+63)-8(n+63)=0 (n-8)(n+63)=0
anonymous
  • anonymous
Now, either n-8=0 n=8 OR n+63=0 n=-63 BUT n cannot be negative So, n=8
anonymous
  • anonymous
got it?
anonymous
  • anonymous
thanks
anonymous
  • anonymous
welcome

Looking for something else?

Not the answer you are looking for? Search for more explanations.