Another question

kreshnik · **Joined:** Sun, 25 Dec 2011 00:28:25 UTC **Posts:** 95

Here's another problem! (Maybe Easy...)
$4*2^x\:=\:5^{x+2}$ , find x=?

I attempted to solve this one but I only got here:

$4*2^x\:=\:5^{x+2}$

$2^2*2^x\:=\:5^{x+2}$

$2^{x+2}\:=\:5^{x+2}$

I really don't know what to do...I tried to solve this one on Microsoft mathematics
but it doesn't actually showed me how to solve it. Only gave me a result that
X=-2

not exactly -2 but approximately (I don't know how to write that sign, I hope you know what I mean)
...Any advice? :oops:

thraiye · **Joined:** Sun, 25 Dec 2011 08:28:42 UTC **Posts:** 12

I think i can help!
Upto where you ended its correct,then from there you are supposed to substitute a value on "x" so as to make the exponent zero(0),since if you make the exponent zero you can get the same value on each side which is one,thus it means the value of "x" you substituted is correct.The only value you can substitute on "x" to make the exponent zero is "-2",thus "x=-2".

kreshnik · **Joined:** Sun, 25 Dec 2011 00:28:25 UTC **Posts:** 95

As much as I understand, you told me this

So...

$4*2^x\:=\:5^{x+2}$

$2^2*2^x\:=\:5^{x+2}$

$2^{x+2}\:=\:5^{x+2}$

$substitute: x=-2 \: \:so \:we\: have:$

$2^{-2+2}\:=\:5^{-2+2}$

$2^0\:=\:5^0$ and we know that..."Example" $5^0\:=\:5^{2-2}\:=\:{5^2}/{5^2}\:=\: 1$

So, this should be like 2^0=5^0

==>

and here's the solution: X=-2

Thank you very much my friend...

Shadow · **Posted:** Tue, 27 Dec 2011 19:23:18 UTC

If you have other questions, make your own topics for them. Topic split.

Denis · **Posted:** Tue, 27 Dec 2011 21:44:49 UTC

kreshnik wrote:

$2^0\:=\:5^0$ and we know that..."Example" $5^0\:=\:5^{2-2}\:=\:{5^2}/{5^2}\:=\: 1$

Keep it simple: x^(2-2) = x^0 = 1

Shadow · **Posted:** Tue, 27 Dec 2011 22:01:51 UTC

Denis wrote:

kreshnik wrote:

$2^0\:=\:5^0$ and we know that..."Example" $5^0\:=\:5^{2-2}\:=\:{5^2}/{5^2}\:=\: 1$

Keep it simple: x^(2-2) = x^0 = 1

Indeed, and of course $x\ne 0$ .

Denis · **Posted:** Wed, 28 Dec 2011 01:34:15 UTC

Shadow wrote:

...and of course $x\ne 0$ .

Why not?
http://www.google.ca/#sclient=psy-ab&hl ... 88&bih=563

Shadow · **Posted:** Wed, 28 Dec 2011 05:03:33 UTC

Denis wrote:

Shadow wrote:

...and of course $x\ne 0$ .

Why not?
http://www.google.ca/#sclient=psy-ab&hl ... 88&bih=563

I don't get that link at all, all I see is Canadian Google.

Denis · **Posted:** Wed, 28 Dec 2011 06:00:33 UTC

You'd see: 0^0 = 1

Shadow · **Posted:** Wed, 28 Dec 2011 06:01:48 UTC

Denis wrote:

You'd see: 0^0 = 1

Oh, don't get me started on "what 0^0 is".

thraiye · **Joined:** Sun, 25 Dec 2011 08:28:42 UTC **Posts:** 12

Yeah,exactly!and you are welcome.

k
reshnik wrote:

As much as I understand, you told me this

So...

$4*2^x\:=\:5^{x+2}$

$2^2*2^x\:=\:5^{x+2}$

$2^{x+2}\:=\:5^{x+2}$

$substitute: x=-2 \: \:so \:we\: have:$

$2^{-2+2}\:=\:5^{-2+2}$

$2^0\:=\:5^0$ and we know that..."Example" $5^0\:=\:5^{2-2}\:=\:{5^2}/{5^2}\:=\: 1$

So, this should be like 2^0=5^0

==>