- #1
Evangeline101
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Homework Statement
Homework Equations
Discriminant: b2 - 4ac
The Attempt at a Solution
a) [/B]f(x) = 3x2 – 5x + 1
y = 3x2 – 5x +1
Substitute a=3, b= -5, c=1 into the discriminant:
b2 – 4ac = (-5)2 – 4(3)(1)
=25 – 12
= 13 This number is positive.
Since b2 – 4ac > 0, there are two real roots, so the quadrative function has two x-intercepts.
b) f(x) = 2x2 + x +1
y = 2x2 + x +1
Substitute a=2, b=1, c=1 into the discriminant:
b2 – 4ac = (1)2 – 4(2)(1)
= 1 – 8
= -7 This number is negative.
Since b2 – 4ac < 0, there are no real roots, so the quadratic function does not have any x-intercepts.
c) f(x) = 4x2 – 12x + 9
y = 4x2 – 12x + 9
Substitute a=4, b= -12, c=9 into the discriminant:
b2 – 4ac = (-12)2 – 4(4)(9)
=144 – 144
= 0
Since b2 – 4ac = 0, there is one (double) real root, so the quadratic function has one x-intercept.
Is this correct?