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Log question watch

1. So the question is 2^(2x) + 2^x - 6 = 0. Can someone explain why I can't put logs in the equation? like e.g make it (2x)log2 + xlog2 - log6 = 0. Int he answers what theyve done is theyve factorised it as if it was a quadratic. :s
2. (Original post by tetra-s)
So the question is 2^(2x) + 2^x - 6 = 0. Can someone explain why I can't put logs in the equation? like e.g make it (2x)log2 + xlog2 - log6 = 0.
If you have

a+b=c

You cannot do

log(a) + log(b) = log(c)

Any more than you can apply any other function

Eg

You cannot do

3. (Original post by tetra-s)
In the answers what theyve done is theyve factorised it as if it was a quadratic. :s

So you have

Which is the equivalent of

4. ^More specifically,

.
5. Ah I see, makes sense now! thanks everyone
6. (Original post by nm786)
yeah with these kind of questions, always make sure you end up with a quadratic so that you can factorise and then easily solve for x.
But with this one either complete the square or use the quadratic formula because .
Actually it does factorise

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