What are the x intercepts for the function y=2x^2 + x - 8?

John McCann answered

Set to zero.

2X^2 + X - 8 = 0

I am too lazy to do anything but use the quadratic formula here.Discriminant looks good for two real roots.

-b +/- sqrt(b^2-4ac)/2a

a = 2
b = 1
c = - 8

X = -1 +/- sqrt[1^2 - 4(2)(-8)]/2(2)

X = -1 +/- sqrt(65)/4

X = - 1 +/- sqrt(8^2 * 1)/4

X = [-1 +/- 8]/4

X = 7/4
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X = - 9/4
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My TI-84 confirms these roots.

Oddman answered

Using the quadratic formula to solve
ax^2 + bx + c = 0
we get
x = (-b ± √(b^2 - 4ac))/(2a)
You have a=2, b=1, c=-8, so
x = (-1 ± √(1 - 4(2)(-8)))/(2*2)
x = (-1 ±√65)/4

x ≈ {-2.26556, 1.76556}

What are the x intercepts for the function y=2x^2 + x - 8?

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