You are Here: Home >< Maths

# indicies watch

1. 2^x+4^x+1=8

How do you solve this?
2. (Original post by judogainz)
2^x+4^x+1=8

How do you solve this?
Having everything with a base of 2^... may help.
3. (Original post by SeanFM)
Having everything with a base of 2^... may help.
taht was what is was thinking how would i get the other one to 2?
4. (Original post by judogainz)
taht was what is was thinking how would i get the other one to 2?
Law of indices.

How can 4^x be written in terms of 2^...? (Hint: 4=2^2)
5. (Original post by SeanFM)
Law of indices.

How can 4^x be written in terms of 2^...? (Hint: 4=2^2)
i know that you square it, but would it go to 2^x+3^2(x+1) ?
6. (Original post by judogainz)
i know that you square it, but would it go to 2^x+3^2(x+1) ?
The 3 should be a 2, but yes, well done
7. (Original post by SeanFM)
The 3 should be a 2, but yes, well done
so you ignore the base and just use the pwoers

Im left with x+2(x+1)=8

do i just solve it from here?
8. (Original post by judogainz)
so you ignore the base and just use the pwoers

Im left with x+2(x+1)=8

do i just solve it from here?
You can't quite jump like that

So the things with x in are now of the form 2^...

Giving you 2^x + 2^(x+2) - 8 = 0, and you know that 2^(x+2) = 2^x * 2^2 by law of indices. After you've changed that, can you think of how to solve it? (Hint: a substitution turns it into a quadratic).

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: November 12, 2015
Today on TSR

### Congratulations to Harry and Meghan!

But did you bother to watch?

Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams