Parabola

**Kayla** · March 1st 2010, 12:08 PM

find the value of the discriminant: Use that number to describe the nature of the roots:

a. 12x^2+2x+5=0

b. x^2+6x=0

2: suppose f(x)=3x^2+2x1
a. find x if f(x)=7
b. find the x-intercepts
c. find f(-4)
d.find (2)

**pickslides** · March 1st 2010, 12:24 PM

for $ax^2+bx+c=0$ the discriminant is $\Delta = b^2-4ac$

When

$\Delta >0$ your quadratic has two distinct real roots

$\Delta =0$ your quadratic has one repeated real root

$\Delta <0$ your quadratic has no real roots

for $12x^2+2x+5=0$ then $a = 12, b=2$ and $c = 5$

so $\Delta = 2^2-4\times 12 \times 5 = \dots$

finish this and make your conclusion.