Precalculus: log equations, log evaluation, etc.

[wiishesssss]

Multiple Choice:

9.) If log a = x and log b = y, what is log (a x Sq. Rt. of b)?

a. x + y / 2 b. x + y/2 c. x + 2y d. 2x + 2y

11.) If log a = 2 and log b = 3, what is the numerical value of log Sq. Rt. of a / b ^ 3 ?

a. 25 b. -25 c. 8 d. -8

12. The expression log(base 3) (8-x) x is defined for all values of x such that

a. x is greater than or equal to 8
b. x is less than or equal to 8
c. x is less than 8
d. x is greater than 8

13. For which value of x is y = log x undefined?

a. 0
b. 1.25
c. .1
d. e

Thank you.

 

[tkhunny]

Re: Precalculus

Multiple Choice:

9.) If log a = x and log b = y, what is log (a x Sq. Rt. of b)?

a. x + y / 2 b. x + y/2 c. x + 2y d. 2x + 2y

Where are these problems coming from? I really do not want to be doing your exam for you.

This first one is fundamental. If you REALLY can't get it, there are bigger problems afoot. Apply the most fundamental rules you know about logarithms.

log(a*b) = log(a) + log(b)

log(b^c) = c*log(b)

That's all you need.

 

[stapel]

9) Is the log expression meant to be "log(ax sqrt)", or something else? Were you given a value for the variable "x"? What is the meaning of the various answer options? For instance, what is the difference between "a. x + y / 2" and "b. x + y / 2"?

11) Is the log expression meant to be "log(sqrt[a]) ÷ b³", or something else?

12) Is the log expression meant to be "[log₃(8 - x)](x)", or something else?

13) The answer to this exercise follows immediately from the definition of "logarithm".

Please reply with corrections, clarifications, and a listing of all of your work and reasoning so far. Thank you.

Eliz.

 

[wiishesssss]

These problems are coming from a multiple choice sheet, AND i am not asking anyone to "do" them for me i just wanted hints as to how to do them because out of all the problems i had to do those were the ones i did not understand.

and yes stapel, for 9 it is suppossed to be log(a xs qrt) ..and all i was given is that log a = x anf log b = y, what is log(a x sqrt)?

For 11. the log expression is meant to be "log(sqrt[a]) ÷ b^3", or something else?

The full question is asking if log a = 2 and log b = 3, what is the numerical value of log(sqrt[a] ÷ b^3 (or b cubed)"?

12. the log expression is meant to be "[log3(8 - x)](x)" -- ** 3 is the base though **

 

[hypoid]

9. If question is log(a*b^1/2) then write answer is x+y/2.
// log(a*b^1/2)=loga+(1/2)logb=x+y/2.

11. log(a^1/2/b^3)=(1/2)loga-3logb=1-9=-8.

12. log(base3)(8-x)x is defined for x belongs to interval from -inf to 8, write answer is C.

13. write answer - a.

 

[wiishesssss]

Thank you so much ..Now i know i got all of my questions correct except for #11

Once again, thank you.