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  3. Chapter 1: Functions of one variable
  4. Exponential and logarithmic functions
  5. Change base
  6. Exercise

Exercise

Determine all the values of $x$ such that $^{64}\!\log 49=^8\!\log x$.
None of the other answers is correct.
$x=15$.
$x=-15$.
$x=7$
Determine all the values of $x$ such that $^{64}\!\log 49=^8\!\log x$.
Antwoord 1 correct
Fout
Antwoord 2 optie
$x=15$.
Antwoord 2 correct
Fout
Antwoord 3 optie
$x=-15$.
Antwoord 3 correct
Fout
Antwoord 4 optie
$x=7$
Antwoord 4 correct
Correct
Antwoord 1 optie
None of the other answers is correct.
Antwoord 1 feedback
Wrong: The correct answer is among them.

Try again.
Antwoord 2 feedback
Wrong: $\dfrac{^{8}\!\log 49}{^{8}\!\log 64}\neq ^{8}\!\log 15$.

See Properties logarithmic functions.
Antwoord 3 feedback
Wrong: $\dfrac{^{8}\!\log 49}{^{8}\!\log 64}\neq ^{8}\!\log (-15)$.

See Properties logarithmic functions.
Antwoord 4 feedback
Correct: $^{64}\!\log 49=\dfrac{^{8}\!\log 49}{^{8}\!\log 64}=\dfrac{^{8}\!\log 49}{2}=^{8}\!\log 7$. Hence, $x=7$.

Go on.