OG 12th edition Q # 45

[bhumika.k.shah]

45. If r is a constant and an = rn for all positive integers n,
for how many values of n is an < 100 ?
(1) a50 = 500
(2) a100 + a105 = 2,050

How can i find out the sequence???

[sanju09]

45. If r is a constant and an = rn for all positive integers n,
for how many values of n is an < 100 ?
(1) a50 = 500
(2) a100 + a105 = 2,050

How can i find out the sequence???

By an, do you mean nth term or what? Can we draw the usual meaning of rn or is it r^n? Please clarify, I don't have that OG.

[bhumika.k.shah]

I actually dont know ... its not raised to - for sure!

its to the right hand side below the alphabet...

i dont even know whats it called as per the "math" way :-S

45. If r is a constant and an = rn for all positive integers n,
for how many values of n is an < 100 ?
(1) a50 = 500
(2) a100 + a105 = 2,050

How can i find out the sequence???

Do you mean a^n = r^n? If yes, then please do the necessary edit all over.

[sanju09]

I actually dont know ... its not raised to - for sure!

its to the right hand side below the alphabet...

i dont even know whats it called as per the "math" way :-S

45. If r is a constant and an = rn for all positive integers n,
for how many values of n is an < 100 ?
(1) a50 = 500
(2) a100 + a105 = 2,050

How can i find out the sequence???

Do you mean a^n = r^n? If yes, then please do the necessary edit all over.

OK....then it is an arithmetic progression with first term r and common difference r.

(1) a50 = r + 49 r = 500 (given), r = 10. Sufficient

(2) a100 + a105 = (r + 99 r) + (r + 104 r) = 2050 (given). r = 10. Sufficient

[spoiler]D[/spoiler]

[sanju09]

I actually dont know ... its not raised to - for sure!

its to the right hand side below the alphabet...

i dont even know whats it called as per the "math" way :-S

It's called SUBSCRIPT

[bhumika.k.shah]

I got wht u did.but dint understand why u did so???

concept please!

I actually dont know ... its not raised to - for sure!

its to the right hand side below the alphabet...

i dont even know whats it called as per the "math" way :-S

45. If r is a constant and an = rn for all positive integers n,
for how many values of n is an < 100 ?
(1) a50 = 500
(2) a100 + a105 = 2,050

How can i find out the sequence???

Do you mean a^n = r^n? If yes, then please do the necessary edit all over.

OK....then it is an arithmetic progression with first term r and common difference r.

(1) a50 = r + 49 r = 500 (given), r = 10. Sufficient

(2) a100 + a105 = (r + 99 r) + (r + 104 r) = 2050 (given). r = 10. Sufficient

[spoiler]D[/spoiler]

[sanju09]

If nth term of a sequence is given by n multiplied to a contant, then it bears the first term and common difference equal to the constant, and hence it's an AP.