Question 183120
Is x=y^4+5 a function?
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Solve for "y":
 
y = (x-5)^(1/4)

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Example: If you let x = 21 you get
y = (21-5)^(1/4)
y = 16^(1/4)
y = 2 or y = -2
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Since there are two y-values for a single value of "x"
x = y^4+5 is not a function.
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Cheers,
Stan H.