# Thread: quicker method -2??

1. Good post? |

## quicker method -2??

If the sequence
x1, x2, x3, …, xn, … is such that x1 = 3 and xn+1 = 2xn – 1 for n 1, then x^20 x19 =

A. 2^19
B. 2^20

C. 2^21

D. (2^20) - 1

E. (2^21 )- 1

2. Good post? |
Can you type the question correctly?

Did you mean
x20 - x19

And is the first equation correct ?
xn+1 = 2xn - 1

3. Good post? |
Can you type the question correctly?

Did you mean
x20 - x19

And is the first equation correct ?
xn+1 = 2xn - 1

4. Good post? |
I think that is what raunekk precisely meant
Answer is A 2^19

I just substituted the value to get the result

X2 = 2*3-1 = 5
X3 = 2*5-1 = 9
X3 - X2 = 2^2

X4-X3 = 2^3
Xn+1 - Xn = 2^n

X20-X19 = 2^19

5. Good post? |
if what the question typed is correct ,,, then its just series of odd no.s and I dont know what he's asking???

6. Good post? |
hey this question have been previously discussed under some different thread

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