You can put this solution on YOUR website! Function notation is an alternate for 'y' notation. That is, f(x) = something is also shown as y = something. The f(x) notion makes it clear the value of f(x) is dependent on the value of x, whereas, 'y' notation gives the impression they're independent.
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The function we have here is a 'cube machine.' You put a value of 'x' into the machine and out comes the cube x*x*x. Of course, we show x*x*x as .
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Given
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f(5) simply means x=5.
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So we can say the 5 cubed = 125.
Done.