Respuesta :

Answer:

Both of those are functions.

Step-by-step explanation:

[tex]y=x^2[/tex] is a parabola that opens up.

Any upward or downward parabola is a function because they pass the vertical line test.

[tex]x=\pm \sqrt{1-y}{/tex]

Square both sides:

[tex]x^2=1-y[/tex]

Subtract 1 on both sides:

[tex]x^2-1=-y[/tex]

Multiply both sides by -1:

[tex]-x^2+1=y[/tex]

So this is a another parabola and it is faced down.  So this is also a function.

[tex]y=ax^2+bx+c[/tex] wit [tex]a \neq 0[/tex] willl always be a parabola.  

If [tex]a>0[/tex] then it is open up.

If [tex]a<0[/tex] then it is open down.

Upwards and downward parabolas will always be functions.

[tex]x=ay^2+by+c[/tex] are also parabolas but these open to the left or right.  These will not be functions because they will not pass the vertical line test.  

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