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# help with solving logarithm watch

1. Hi, ive had a crack at solving this logarithm but it has stumped me.

Solve for x:
log x +log(x +1)=log30 (the logs are log base 10)

My progress:
log x +log(x +1)=log30
log(x*(x+1) =log30
log(x²+1x) =log30

not sure where to go from here

Many thanks for any assistance
2. You can say: x²+x = 30 and solve from there.
And when you solve, make sure that x is positive, because otherwise log(x) doesn't exist.
Good luck.
3. x^2 + x = 30

Edit: Ninja'd by oliv3r x]
4. Thanks chaps, I got it solved with your help.

x²+x-30=0
(x+6)(x-5)=0 (factorise)
x=+5 or x=-6
But x cannot be negative "because otherwise log(x) dosen't exist" (TY oliv3r)
Therefore x = +5
The answer in the book agrees.

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