A-Level Maths : Logarithms : Equations 3 : ExamSolutions

[rudeboirascal11]

i have a found an easier solution,, if you take log4tothebase9 over so you get 3-log4tothebase9 = logxtothebase3 you get 2.369070246 = log(x)tothebase3 now if you do 3^2.369070246 = x therefore you get the same answer that you give 13.5. now i am just wondering can this rule be applied to the same sort of question or is it ancoincident

[ExamSolutions]

@rudeboirascal11 You can apply it. There is often more than 1 way of solving an equation.

[RShahProductions]

@ExamSolutions Hey mate, before I ask just thought I should say your site and these videos are excellent and will really get me through c2, m1 and if need be, c1 for the retake depending on my (likely not-so-good) result.. thank you!

My question is, would there be any circumstance I couldn't just use rudeboirascal11's method, as opposed to the method you've applied here??

[ExamSolutions]

@RShahProductions Of course you can.

[mandarkm]

sorry...the question is will it be plus or minus square root of 3^6 / 4??thank u for ur videos sooo much..its helpin me a lot..m from this lil country in asia called maldives

[ExamSolutions]

@mandarkm Good question. It cannot be minus because if you go back to the first line where it says log x you would get an error when you try to log it on a calculator. You cannot log a negative number. Hope that helps?

[mandarkm]

@ExamSolutions thank you

[mandarkm]

i hav a question...for the first part do we have to plus or minus 3^6/4

[abdus110]

when uv multipled the second part with base 9 by 2 hw cum u havent multiplied the whole equations like u did with the last one? cause i can see u got the right answer but im confused why u didnt.

plz reply really puzzled me

[ExamSolutions]

@abdus110 Sorry but I am confused by your question

[ossielmais]

@ExamSolutions at 6:56 where log^9 x is devided by 1/2, you multiplied by 2, however you didn't multiply the WHOLE equation, only the expression to get 2log^9 x. Can you please explain what you did there?

[ExamSolutions]

@ossielmais I was cleaning up the one term. Dividing by 1/2 is the same as multiplying the top by 2. Take 6 divided by 1/2. How many times can you fit 1/2 into 6? Answer 12 times.

[add3451]

@abdus110 it is not multiplied by two, but instead just that part is divided by half which is effectively multiplied by two but it is only that part not the whole equation

[Xplosiv3s]

you are soo awesome!!!!!!!!!!!!!

[TheFlomosapien]

If log10 x + log10 y = 3, then xy =?

[ExamSolutions]

@TheFlomosapien log 100xy=3 so 100xy = 10^3, so 100xy = 1000 so xy = 10

[mushinart]

coool example, sir :)

bless your heart for the great effort

[mbk2905]

Great video !

Quick qn on the topic:

- how would you simply write:

log (base a) [x + y]

does it = log (base a) [x] + log (base a) [y]

OR

log (base a) [x] times log (base a) [y]

thanks

[ExamSolutions]

@mbk2905 neither. It stays the same.

[mbk2905]

Great video !

Quick qn on the topic:

- how would you simply write:

log (base a) [x + y]

does it = log (base a) [x] + log (base a) [y]

OR

log (base a) [x] times log (base a) [y]

thanks

[nipponpaint99]

great!

[Y5FK]

in my formula book i got given as LOGa b = LOGb b / LOGb a but then it writes LOGa b = 1/LOGb a i get what it means becuase any log in the same base is 1 but can that formula(LOGa b=1/LOGb a) be used aswell to solve in different bases ?

[ExamSolutions]

Depends on the question. It will restrict your base change. Whereas the formula log(a)N = log(b)N/log(b)a allows you to switch to any base as I have introduced a third variable N.

[Y5FK]

@ExamSolutions Many thanks, I wish you was my maths teacher

[sloth245]

how do u get so good at math.

[ExamSolutions]

practice, patience, determination to not give up, enjoying the challenge of getting an answer, a good teacher.

[rage11761]

Thank you! Very helpful

[love2laugh35]

nice!! thanks this is very helpful

[ExamSolutions]

Thank you for your comment