1)log3(x^2-3x-1)=0 2)-logx(25)=-2 =x^-2=25 i know the base is 5 but confused whether it is negative or positive. thanks
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Originally Posted by smmmc 1)log3(x^2-3x-1)=0 for b > 0, so becomes . Solve the quadratic: 2)-logx(25)=-2 =x^-2=25 i know the base is 5 but confused whether it is negative or positive. First get rid of the negative signs: . As you said, x = 5 (and it's positive). 01
Last edited by yeongil; Jul 18th 2009 at 03:50 AM.
b>1 always apply ? what about when b<1 ? thanks heaps
Oops, typo. I meant b > 0 and b ≠ 1. Of course, in logarithms you can't have a negative base (b < 0). 01
Last edited by yeongil; Jul 18th 2009 at 05:26 AM. Reason: because I'm sleep deprived. :(
You can't have a base of 1 either
If the original problem had been then it would have been so that and , still positive.
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