Question

how many times does the graph of the function below touch or cross the x-axis?
3x^2+8x+5

Answer 1

do you know how to do it

Answer 2

How many times do you think it crosses the x-axis?

Answer 3

i have no idea

Answer 4

Use the discriminant test b^2 - 4ac to figure it out.

If the discriminant is negative, then it crosses zero times
If the discriminant is zero, then it crosses one time.
If the discriminant is positive, then it crosses two times

Answer 5

i got -4

Answer 6

os my final answer is zero

Answer 7

a = 3
b = 8
c = 5

b^2 - 4ac = (8)^2 - 4(3)(5) = 64 - 60 = 4

That's what I get

Answer 8

ok so it zero right i know the answer is 4 but it tells me how many times i cross so the answer is zero

Answer 9

Re-read what I wrote @romanortiz65

Answer 10

@DebbieG, allow @romanortiz65 to figure this out on his own.

Answer 11

@romanortiz65, I'm waiting for you to respond again.

Answer 12

What is the connection between the discriminant and the touching/crossing behavior? Remember - it's a quadratic, so the shape of the graph is a parabola.

If discr>0, there are 2 DISTINCT real roots - what does that mean in terms of it's behavior crossing/touching the axis?

If discr=0, there is ONE REPEATED real root - what does that mean in terms of it's behavior crossing/touching the axis?

if discr<0, there are NO REAL roots (only complex roots) - what does that mean in terms of it's behavior crossing/touching the axis?

Answer 13

i got it 2

Answer 14

@Hero I don't give answers. Was just trying to help him think about it.

Answer 15

but I was already helping him

Answer 16

gut no fight aight its cool i got thanks