Menu Close

The-sum-of-the-first-and-last-term-of-an-A-P-is-51-And-the-sum-of-the-progression-is-255-Find-the-last-term-of-the-A-P-




Question Number 11399 by tawa last updated on 23/Mar/17
The sum of the first and last term of an A.P is 51. And the sum of the   progression is 255. Find the last term of the A.P.
$$\mathrm{The}\:\mathrm{sum}\:\mathrm{of}\:\mathrm{the}\:\mathrm{first}\:\mathrm{and}\:\mathrm{last}\:\mathrm{term}\:\mathrm{of}\:\mathrm{an}\:\mathrm{A}.\mathrm{P}\:\mathrm{is}\:\mathrm{51}.\:\mathrm{And}\:\mathrm{the}\:\mathrm{sum}\:\mathrm{of}\:\mathrm{the}\: \\ $$$$\mathrm{progression}\:\mathrm{is}\:\mathrm{255}.\:\mathrm{Find}\:\mathrm{the}\:\mathrm{last}\:\mathrm{term}\:\mathrm{of}\:\mathrm{the}\:\mathrm{A}.\mathrm{P}. \\ $$
Answered by ajfour last updated on 23/Mar/17
last term = (1/2)(51+9d)  where d is whatever common  diffeeence you choose..  number of terms n=10  The first term a= (1/2)(51−9d)
$$\mathrm{last}\:\mathrm{term}\:=\:\frac{\mathrm{1}}{\mathrm{2}}\left(\mathrm{51}+\mathrm{9d}\right) \\ $$$$\mathrm{where}\:\mathrm{d}\:\mathrm{is}\:\mathrm{whatever}\:\mathrm{common} \\ $$$$\mathrm{diffeeence}\:\mathrm{you}\:\mathrm{choose}.. \\ $$$$\mathrm{number}\:\mathrm{of}\:\mathrm{terms}\:\mathrm{n}=\mathrm{10} \\ $$$$\mathrm{The}\:\mathrm{first}\:\mathrm{term}\:\mathrm{a}=\:\frac{\mathrm{1}}{\mathrm{2}}\left(\mathrm{51}−\mathrm{9d}\right) \\ $$
Commented by tawa last updated on 24/Mar/17
God bless you sir.
$$\mathrm{God}\:\mathrm{bless}\:\mathrm{you}\:\mathrm{sir}. \\ $$$$ \\ $$

Leave a Reply

Your email address will not be published. Required fields are marked *