text: # Thread: Variable with exponential equation help
  
  1. ## Variable with exponential equation help
  
  Hi there, I seem to be having trouble with this equation. (X^3+5)/4=8
  
  My idea was to multiply the values inside the bracket by 4 to undo the division, and then to do the same to the RHS...ie. 4x8, and work from there...but this gave me x= 1.4422495
  
  But this method does not work out. I used my casio Classpad 330 to solve the equation, and x=3
  
  Can someone give me a heads up where I am going wrong
  
  2. ## Re: Variable with exponential equation help
  
  Hello, Tren301!
  
  Hi there, I seem to be having trouble with this equation: . $\frac{x^3+5}{4}\:=\:8$
  
  My idea was to multiply the values inside the bracket by 4 to undo the division . What?
  and then to do the same to the RHS ... ie, 4x8, and work from there ... but this gave me x= 1.4422495
  
  But this method does not work out. I used my casio Classpad 330 to solve the equation, and x=3
  
  Can someone give me a heads up where I am going wrong?
  
  We are given: . $\frac{x^3+5}{4} \:=\:8$
  
  Multiply by 4: . ${\color{red}4}\cdot\frac{x^3+5}{4} \:=\:{\color{red}4}\cdot8$
  
  And we have: . $x^3 + 5 \:=\:32 \quad\Rightarrow\quad x^3 \:=\:27 \quad\Rightarrow\quad x \:=\:3$
  
  3. ## Re: Variable with exponential equation help
  
  $\displaystyle \frac{x^3+5}{4}=8$
  
  $\displaystyle x^3+5=8\times 4$
  
  $\displaystyle x^3+5=32$
  
  $\displaystyle x^3=32-5$
  
  $\displaystyle x^3=27$
  
  $\displaystyle x=\sqrt[3]{27} = 3$
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