How do you find the vertex of #y= -2(x+3)(x-1)#?

1 Answer
Jim G.
May 15, 2018

#"vertex "=(-1,8)#

Explanation:

#"the vertex lies on the axis of symmetry which is "#
#"positioned at the midpoint of the zeros"#

#"to find the zeros set "y=0#

#rArr-2(x+3)(x-1)=0#

#"equate each factor to zero and solve for "x#

#x+3=0rArrx=-3#

#x-1=0rArrx=1#

#x_"vertex"=(-3+1)/2=-1#

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

#y_"vertex"=-2(2)(-2)=8#

#rArrcolor(magenta)"vertex "=(-1,8)#

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