
Jonathan W. answered 05/27/15
Tutor
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Patient and Knowledgeable Berkeley Grad for Math and Science Tutoring
I have just the right temperament to enjoy drawing these things carefully.
Start by graphing, lightly, y = 2(x-3)(x+1). It should be a parabola with
x-intercepts (3,0) and (-1,0),
y-intercept (0, 2(0-3)(0+1)) = (0, -6)
vertex ((3+-1)/2, 2((3+-1)/2-3)((3+-1)/2+1) = (1, 2(1-3)(1+1)) = (1, -8)
[1 is halfway between -1 and 3 on the x-axis, and -8 is its corresponding y-value on the parabola.]
To graph y = |2(x-3)(x+1)|, leave all the parts above the x-axis where they are
[For example, the point (4, 10) becomes (4, |10|) remains (4, 10).]
and take all the parts below the x-axis and flip them.
[For example, the point (1, -8) becomes (1, |-8|) = (1, 8).]
Then darken those parts at or above the x-axis. [It should be sort of a W shape.]
Josh F.
05/27/15