what is x

[deepoe]

2^x – 2^x-2 = 3(2^13), what is x?
a. 9
b. 11
c. 13
d. 15
e. 17





Don't know if this question already have been asked, if so I'M SORRY

[DanaJ]

2^(x-2) is a common factor for 2^x and 2^(x-2), so you get:

2^x - 2^(x-2) = 2^(x-2) * [2^2 - 1] = 2^(x - 2) * (4 - 1) = 2^(x - 2) * 3 = 3 * 2^13

This means that x - 2 = 13, so x = 15.

And yes, I do believe this question has been answered before...

[dumb.doofus]

[deepoe]

I don't understand this:


2^(x-2) * [2^2 - 1] = 2^(x - 2) * (4 - 1) = 2^(x - 2) * 3 = 3 * 2^13


You got: 2^x - 2^(x-2) But how you get [2^2 - 1] ?

[kanha81]

2^x – 2^x-2 = 3(2^13), what is x?
a. 9
b. 11
c. 13
d. 15
e. 17





Don't know if this question already have been asked, if so I'M SORRY

Deepoe,
Please type your questions clearly!!!

A better way to write this out would be:
Notice the highlighted part!!!!
2^x - 2^(x-2) = 3 (2^13)

2^x * (1- (1/2^2) ) = 3 * (2^13)
2^x * (3/4) = 3 * (2^13)
2^x = (2^2) * (2^13)
2^x = 2^15
x = 15

[D]

[deepoe]

2^x – 2^x-2 = 3(2^13), what is x?
a. 9
b. 11
c. 13
d. 15
e. 17





Don't know if this question already have been asked, if so I'M SORRY

Deepoe,
Please type your questions clearly!!!

A better way to write this out would be:
Notice the highlighted part!!!!
2^x - 2^(x-2) = 3 (2^13)

2^x * (1- (1/2^2) ) = 3 * (2^13)
2^x * (3/4) = 3 * (2^13)
2^x = (2^2) * (2^13)
2^x = 2^15
x = 15

[D]

Sorry

Could you explain these steps:

2^x * (1- (1/2^2) ) = 3 * (2^13)
2^x * (3/4) = 3 * (2^13)

Thanks!

[deepoe]

ah already understand it


2^(x-2) = 2^x * 2^-2

So you get 2^x - 2^x * 2^-2