luk3tm Posted April 15, 2009 Report Share Posted April 15, 2009 just been doing some revision for the final exams and wondering about these questions on logarithmssolve for x:log4 x^3 + log2 x^(1/2) =8 (the answer in the back of the book is apparently 16 but im not sure why)similar question:log 16 x^5=log64 125 -log 4 X^(1/2)note that the numbers closest to the log should be in subscriptits maths SL btw if you need to know Reply Link to post Share on other sites More sharing options...
Abu Posted April 15, 2009 Report Share Posted April 15, 2009 You need to use the change of base formula and then solve for x using normal log rules. Reply Link to post Share on other sites More sharing options...
Jenna Posted April 16, 2009 Report Share Posted April 16, 2009 use the change of base rule for the first bit of the equation ie for log(base4) x^3change the base to base 2, which is the same base as in the second part of the equation. You will get [log(base2)x^3] /[ log(base2)4] which works out to[ log(base2)x^3]/2then you can use the rule log(base2)x^n = n log(base2)x to alter the first 2 bits of the equationgetting 3/2 log(base2)x + 1/2 log(base2)x =8you should be able to finish it from there Reply Link to post Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.