Answer:
Function: [tex]x+y=9[/tex]
Not Function: [tex]x^2+y^2=1[/tex] and [tex]x=y^2[/tex]
Step-by-step explanation:
Given
[tex]x+y=9[/tex]
[tex]x^2+y^2=1[/tex]
[tex]x=y^2[/tex]
Required
Determine if [tex]y[/tex] is a function of [tex]x[/tex]
Solving x+y=9
[tex]x+y=9[/tex]
Make y the subject of formula
[tex]y = 9 - x[/tex]
Hence; y is a function of x
Solving [tex]x^2+y^2=1[/tex]
[tex]x^2+y^2=1[/tex]
Subtract x² from both sides
[tex]y^2=1 - x^2[/tex]
Square root of both sides
[tex]y =\± \sqrt{1 - x^2}[/tex]
This implies that
[tex]y =\sqrt{1 - x^2}[/tex] or [tex]y =-\sqrt{1 - x^2}[/tex]
Because [tex]y[/tex] can be any of those two expressions, it is not a function.
Solving [tex]x=y^2[/tex]
[tex]x=y^2[/tex]
Reorder
[tex]y^2 = x[/tex]
Take square roots
[tex]y = \±\sqrt{x}[/tex]
This implies that
[tex]y = \sqrt{x}[/tex] or [tex]y = -\sqrt{x}[/tex]
Because [tex]y[/tex] can be any of those two expressions, it is not a function.
