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# P2 log question, Exam style watch

1. log (base 2) x - log (base 4) y = 4
log (base 2) (x - 2y) = 5.
Solve the simultaneous equations? Good Luck
can u write the steps cos i dont get the right answer!!!
answer: x = 64, y = 16
2. Arrrrggggghhhhhh!!!!!!!!!!!!!!

I think there must be an error in the question, or what you typed...I CAN'T get the answers you give...

This is the rearrangement I do:

log (base 2) (x - 2y) = 5
x - 2y = 2^5
x = 2^5 +2y OR y = 1/2x - 16

I then do this with the other:

log (base 2) x - log (base 4) y = 4
2log (base 4) x - log (base 4) y = 4
log (base 4) x^2 - log (base 4) y = 4
x^2 - y = 4^4

Substitute:

x^2 - 1/2x + 16 = 256
x^2 - 1/2x - 240 = 0

However I can't get a nice round answer from any substitution of that nature...

btw. In case you are confused about my rearrangement of the equation with the two bases; the trick is to use the fact that any power of 4 that gives "x" is half the power of 2 that gives that same "x", because 2^2 = 4.

>log (base 4) x^2 - log (base 4) y = 4
>x^2 - y = 4^4

it should be:
log (base 4) x^2 - log (base 4) y = 4

(x^2)/y = 4^4

etc.......

Dont you dare make that mistake tommorow....

Mrm.

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