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indicies

2^x+4^x+1=8

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

How do you solve this?


Having everything with a base of 2^... may help. :smile:
Reply 2
Original post by SeanFM
Having everything with a base of 2^... may help. :smile:


taht was what is was thinking how would i get the other one to 2?
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)
Reply 4
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) ?
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 :borat:
Reply 6
Original post by SeanFM
The 3 should be a 2, but yes, well done :borat:


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?
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 :redface:

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).

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