Exponential equations homework

[enibaraliu]

Homework Statement

Please , can anybody help me to do these and to explan to me?
I tried tried, but i can't do anything.


1. 4^x-1 + 4^x + 4^x-1=84
2. 15 * 2^x+1 + 15 * 2 ^x-1 =135
3. 8^x + 18= 2* 27^x
4. 3^x-8*3^x/2 +15=0
5. 5^x - 5^3-x=20

Homework Equations

At the 5^th i do like this:
5^x - 5^3-x=5*4 /5
5^x-1-5^2-x=4 and i can't do more, i have just learn for exponential equations and I don't know so good , and that is the reason that i want to help me.the problem is that i want to solve,thanks

The Attempt at a Solution

 

[HallsofIvy]

I'm glad to hear you have tried. What have you tried? We can't make suggestions if we don't know what you already know about the problems or what you already tried. Show us what you have done.

It would also help if you told us exactly what the problems are! You give a list of equations. Are you trying to solve the equations? And please use parentheses to clarify what you mean. I would tend to interpret "4^x-1" as 4^x-1. Do you mean 4^(x-1) which is 4^x-1?

 

[muppet]

Do you know what a logarithm is?

 

[enibaraliu]

muppet , i sad before , i have just learned for exponential equations , and I don't know soo good, and if you know better please help to solve these , thank you