We have that
y = -5/8 x²- 3x + 4----> multiply by 8----> 8y=-5x²-24x+32
8y-32=-5x²-24x
Factor the leading coefficient
8y-32=-5*(x²+4.8x)
Complete the square Remember to balance the equation
by adding the same constants to each side.
8y-32=-5*(x²+4.8x+5.76-5.76)
8y-32-28.8=-5*(x²+4.8x+5.76)
8y-60.8=-5*(x+2.4)²
8*(y-7.6)=-5*(x+2.4)²
-(8/5)*(y-7.6)=(x+2.4)²
-(1.6)*(y-7.6)=(x+2.4)²
is a vertical parabola-----> open down
The standard form is (x - h)²<span> = 4p (y - k)
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the vertex is the point (-2.4,7.6)
4p=-1.6
p=-1.6/4----> p=-0.40
<span>the directrix is
y= k - p-------> 7.6-(-0.40)----> y=7.6+0.40----> y=8
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the answer isy=8
<span>The minus sign of the z-score shows that the score is below the mean.
6 points below the mean means the difference of the score and mean is -6
z = (X-Mean)/SD
-0.50 = -6 / SD
SD = -6/-0.50 = 12
The population standard deviation = 12</span>
<span> <span>x > -7 was the best answer i could do, i hope this helps!</span></span>
this is the answer I came up with hopes this helps