Use the discriminant to determine how many x-intercepts the graph of the equation has.

y = – 4x2 + 3x + 2

A. zero
B. one
C. two
D. three

Question

Use the discriminant to determine how many x-intercepts the graph of the equation has.

y = – 4x2 + 3x + 2

A.  zero
B.  one
C.  two
D.  three

anonymous · Answer

do you know the formula of discriminant?

anonymous · Answer

the discriminant is 41

anonymous · Answer

not really, had to look that up.

anonymous · Answer

no it's okay 

you don't have to look that's what I'm here for lol

anonymous · Answer

alright 

$$D = b^2 - 4ac $$

anonymous · Answer

that is the formula

anonymous · Answer

ok

anonymous · Answer

what you've been give is a quadratic formula 
you know how a quadratic formula looks like right?

anonymous · Answer

yeah

anonymous · Answer

alrighty if you click on this link, you will know what exactly are those a, b and c are in the Discriminant formula http://www.gradeamathhelp.com/image-files/quadratic-formula-abc.gif

anonymous · Answer

either my brain aint working or that doesn't look right?

anonymous · Answer

probably me

anonymous · Answer

mmm which part is it that you're having difficulty?

anonymous · Answer

do you mean a, b, c are in discriminent form?

anonymous · Answer

okay

anonymous · Answer

a,b and the c are the coefficients

anonymous · Answer

coefficients meaning any number that is in front of the x

anonymous · Answer

like 2 is the coefficient in 2x

anonymous · Answer

yeah

anonymous · Answer

so now look at the coefficients in your equation and tell me what are they?

anonymous · Answer

$$y = -4x^2 + 3x + 2$$

anonymous · Answer

4, 2, & 3?

anonymous · Answer

yupppp!

so which one is the a and the b and the c? 

(according to the link I gave you)

anonymous · Answer

4 = a, 3 = b, and 2 = c?

anonymous · Answer

yup!!

you're doing very good :)

anonymous · Answer

Thank you

anonymous · Answer

now if we plug in the numbers into our discriminant formula which is 

$$D = b^2 - 4ac$$

anonymous · Answer

we will get 

$$D = 3^2 - (-4*4*2)$$

anonymous · Answer

D equals???

anonymous · Answer

okay

anonymous · Answer

so what do we get for D?

anonymous · Answer

41

anonymous · Answer

Correct!!! :D

anonymous · Answer

now to answer your main question

a quadratic equation will always give you a graph that looks like U 
(the way how you know it's a quadratic if it has a $$x^2 $$ and a x

anonymous · Answer

okay

anonymous · Answer

and if your D is more than zero 

there are two places that graph intersect like this:

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