How do you find the vertex and the intercepts for #Y=x^2-2x-6#?

1 Answer
Sep 1, 2017

#"see explanation"#

Explanation:

#"given the equation of a parabola in standard form"#

#•color(white)(x)y=ax^2+bx+c color(white)(x);a!=0#

#"then the x-coordinate of the vertex is"#

#x_(color(red)"vertex")=-b/(2a)#

#y=x^2-2x-6" is in standard form"#

#"with "a=1,b=-2,c=-6#

#rArrx_(color(red)"vertex")=-(-2)/2=1#

#"substitute this value into the equation for y"#

#rArry_(color(red)"vertex")=1-2-6=-7#

#rArrcolor(magenta)"vertex "=(1,-7)#

#color(blue)"for intercepts"#

#• " let x = 0, in equation for y-intercept"#

#• " let y = 0, in equation for x-intercepts"#

#x=0toy=-6larrcolor(red)" y-intercept"#

#y=0tox^2-2x-6=0#

#"solve for x using the "color(blue)"quadratic formula"#

#x=(2+-sqrt(4+24))/2#

#color(white)(x)=(2+-sqrt28)/2#

#color(white)(x)=(2+-2sqrt7)/2=1+-sqrt7#

#rArrx~~ -1.65,x~~ 3.65larrcolor(red)" x-intercepts"#
graph{x^2-2x-6 [-20, 20, -10, 10]}