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First term of an A.P is …

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First term of an A.P is -2 and thR 10 th term is 16. Determine the 100th term.

  • 2 answers

Hans Raj 8 years, 5 months ago

Given    

1st term a1 = -2 ,  ..............10th term a10 = 16 , .................100th term  a100 = ?

we know that  

 an = a1 + (n -1)d  ...........   a10 =a1 + (10 - 1) d...................... 16 = -2 + 9d ..................... d = 18/9 ....... .... d = 2

a100 = a1 + (100 - 1) 2...........a100 = -2 + 99x2 ........................ a100 = -2 + 198 ............... a100 = 196      

Payal Singh 8 years, 5 months ago

First term of AP a = -2

Let common difference = d

As we know

{tex}a_n = a+(n-1)d{/tex}

=> {tex}a_{10} = a+(10-1)d{/tex}

=> 16 = -2+9d

=> 9d= 18

=> d= 2

{tex}a_{100} = a+99d{/tex}

=> {tex}a_{100}=-2+(99\times 2){/tex}

{tex}=>> a_{100}= -2+198=196{/tex}

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