If the sum of n terms of an AP is 2n^2+5 then prove that an=4n+3
(ARITHMETIC PROGRESSION)
Answers
Answered by
1
I think there is something wrong in question...pls check once again
Attachments:
Sanco09:
Should *
Is it?
no actually its given 2n^2+5 itself...
It has to be 5n only then it it can be proved
W8 let me show u
k...
yeah u r right..
even now i got thr correct answer when i solved it...
Check attachment
Pls mark brainliest
Answered by
1
Sry, The ques should be If the sum of n terms of an AP is 2n^2+5n then
prove that an=4n+3
_______________________________________________________
Let here no of terms be of the form "x" instead of "n"
Then,
Formula to be used:
aₓ = Sₓ - S₍ₓ₋₁₎
_______________________________________________________
Sₓ = 2x² + 5ₓ
_______________________________________________________
S₍ₓ₋₁₎ = 2(x-1)² + 5(x-1)
= 2(x² - 2x + 1) + 5x - 5
= 2x² - 4x + 5x + 2 - 5
= 2x² + x - 3
_______________________________________________________
Then,
aₓ = (2x² + 5x) - (2x² + x - 3)
= 2x² + 5x - 2x² - x + 3
= 4x + 3
Hence proved
________________________________________________________
☺☺☺ Hope this Helps ☺☺☺
prove that an=4n+3
_______________________________________________________
Let here no of terms be of the form "x" instead of "n"
Then,
Formula to be used:
aₓ = Sₓ - S₍ₓ₋₁₎
_______________________________________________________
Sₓ = 2x² + 5ₓ
_______________________________________________________
S₍ₓ₋₁₎ = 2(x-1)² + 5(x-1)
= 2(x² - 2x + 1) + 5x - 5
= 2x² - 4x + 5x + 2 - 5
= 2x² + x - 3
_______________________________________________________
Then,
aₓ = (2x² + 5x) - (2x² + x - 3)
= 2x² + 5x - 2x² - x + 3
= 4x + 3
Hence proved
________________________________________________________
☺☺☺ Hope this Helps ☺☺☺
TQ Sanjanashetty it became my 400th math ans TQ for Asking ques
Welcome
If u find it as most helpful pls mark it as brainliest
Similar questions