How do you find the vertex and intercepts for y^2+6y+12x+33=0y2+6y+12x+33=0?

1 Answer
Feb 13, 2017

"Vertex" -> (x,y)=(-2,-3) larr" graph of shape "supVertex(x,y)=(2,3) graph of shape

x_("intercept")->(x,y)=(-11/4,0)xintercept(x,y)=(114,0)

y_("intercept")-> "none"yinterceptnone

Explanation:

This is a quadratic in yy instead of xx

So yy is the independent variable. The consequence is that the graph of type uu is rotated clockwise by 90^o90o

Being given this question suggests that your mathematical manipulation skills are more than basic. So not a lot of explanation is given.

12x=-y^2-6y-3312x=y26y33

color(red)("Correction:")Correction: as y^2y2 is negative so the graph type of uu would be rotated 90^o90o anticlockwise giving shape sup

x=-1/12y^2-1/2 y-11/4x=112y212y114

color(blue)("Determine the x-intercept")Determine the x-intercept
Instead of -11/4114 being the intercept of the y-axis it is the intercept of the x-axis

color(blue)("Determine the y-intercept")Determine the y-intercept

The determinant of form
b^2-4ac""->""(-1/2)^2-4(-1/12)(-11/4) = +1/4-11/12b24ac(12)24(112)(114)=+141112

=-2/3=23

As the determinant is negative there is no y-intercept
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
color(blue)("Determine vertex")Determine vertex

Write as:" "x=-1/12(y^2 +12/2y)-11/4 x=112(y2+122y)114

Consider the 12/2122 from 12/2y122y

=>y_("vertex")=(-1/2)xx12/2 = -3yvertex=(12)×122=3

Substituting y=-3y=3

x_("vertex")=-1/12(-3)^2-1/2(-3)-11/4 xvertex=112(3)212(3)114

x_("vertex")= -3/4 +3/2-11/4 = -2 xvertex=34+32114=2

"Vertex" -> (x,y)=(-2,-3)Vertex(x,y)=(2,3)

Tony B