Y=2x or second power is it a function

Question

Is y=2x² a dunction

 

 

Answer 1

y = 2x²  is a parabola that opens upward.

 

There is no value x that produces two possible values y, therefore it passes the vertical line test and is a function.

 

2y² = x would be a parabola opening to the right.  A given non-zero value of x, say 2, would have two values of y.  These points (2,1) and (2, -1) would fail the vertical line test, so a rotated parabola is not a function (unless you rotated it exactly 180º).