Please help!

[Abdinasir Kadawo]

Can anyone help me solve this Logarithm Equation:

 

4^x + 6 * 2^x = 8

 

 

Mahadsanidiin!

[Aaliyyah]

4^x + 6^2x = 8

 

xlog4 + 2xlog6= log8

 

x(log4 + 2log6)= log8

 

x= log8/(log4+2log6)

 

x=0.418

 

 

hope that helps. Good luck.

 

wa salaamu alaikum

[Cara.]

Aaliyah, I think you didn't copy the starting equation right.

 

The left side is

 

log(4^x + 6*2^x)

 

because we can only take the log of the entire term, and this cannot be re-written as

 

log4^x + log(6*2^x)

 

ie, log(x+y) is NOT equal to log(x) + log(y)

 

Maybe you're only supposed to get an approximate answer?

[Baluug]

Uuuuuuhhhhhhhhh......the answer is purple.

[Aaliyyah]

4^x + 6 * 2^x=8

 

xlog4+6xlog2=8

 

x(log4+6log2)=log8

 

x= log8/ (log4+6log2)

 

x=0.375

 

am sorry about earlier it seems I wrote down your equation wrong as I was actually rushing out.

 

 

Wa salaamu alaikum

[Suldaanka]

^^

Good effort but that is incorrect Aaliyah.

 

Here is the answer:

 

I assumed there was a plus somewhere in my calculations... I will revise it and post again soon.

[Aaliyyah]

^^lets see what you got walaal...

[Sir-Qalbi-Adeyg]

I get x=log(8)-log(6)/(log(2)+log(4)).

 

Just plug that in a calculator, and see what you get.

[RedSea]

the sis/bro is cheating, ya'll gonna help her/him cheat.

 

gave him/her the formula and let her/him figure out the rest.

[Pucca]

I get cramps looking at math problems...

[Suldaanka]

Originally posted by AAliyah416:

^^lets see what you got walaal...

For some reason, I am getting (2^x = 1) hence x = 0 since log2(1) = 0. But when I put that answer back into the equation it just doesn't satisfy the answer. For example, when x=0,

 

4^0 + 6 * 2^0 = 8

1 + (6*1) = 8

7 is not 8

 

 

As for your answer:

 

4^(0.375) + (6*2^0.375) = 8

1.69 + 7.78 = 8

9.47 is not 8

 

Somewhere I am doing something wrong. It is been long time since I last opened my maths text book.

 

The answer for x needs to be proven by putting it back into the f(x) equation.

[Malika]

^The poor guy is probably more confused now then when he asked for help..

[N.O.R.F]

Nerds :rolleyes:

[Abdinasir Kadawo]

Sorry bros n sis I made terrible mistake. This is the correct equation: 4^x - 6*2^x + 8 = 0. It was innocent typing error.

 

But anyway I got it now. Substitute 2^x = t and you will get

 

t^2 - 6t + 8 = 0

 

It gives you t1 = 4 and t2 = 2 and you should get

x1 = 2 and x2 = 1.

 

I welcome other methods.

 

Mahadsanidiin

[Abdinasir Kadawo]

thanks all