How do you find the vertex and intercepts for #x = 1/-32y^2#?

2 Answers
Mar 16, 2017

Vertex#->(x,y)=(0,0)#

The intercepts are only at 1 point, the origin

The axis of symmetry is the x-axis ie #y=0#

Explanation:

This is a quadratic in #y# instead of #x#

So instead of form type #y=ax^2+bx+c ....EquationType(1)#
#" we have: " x=ay^2+by+c...EquationType(2)#

Type 1#->nn" or "uu#
Type 2#-> sub" or "sup#

Instead of the horse shoe type shape being up or down it is left or right.

As the coefficient of #y^2# is negative the general shape is #sup#

Consider equationtype(1): The #b# from #bx# moves the graph left or right in that #x_("vertex")=(-1/2)xxb#

Consider equationtype(2); The #b# from #by# moves the graph up or down in that #y_("vertex")=(-1/2)xxb#

However, in this graph #b=0# so the axis of symmetry coincides with the x-axis.

y-intercept is at #x=0#

#=>0=-1/32 y^2" "=>" "y=0# which is only 1 value (single point) so the graph does not #ul("cross")# the y-axis but the axis is tangential to the vertex.

Tony B

Jul 25, 2017

If you write the Parabolic Equation in the form #y = ax^2 + bx + c#
then the x value for the vertex will be = - b / 2a.
For the x intercept, set y=0, in the equation
For the y intercept, set x=0,

Explanation:

If you then plug "- b / 2a " in to the equation you will get the y value and thus the vertex coordinates.
Vertex = ( -b/2a , f ( -b/2a) )

The reason this is true is that the vertex is where the slope = 0 and you can find this by setting the derivative = 0
The derivative is 2ax + b
Setting it = 0 ==> x = -b/2a