Question

Please help?
Calculate the discriminant.

x^2 – 2x + 4 = 0

Answer 1

\[\Large ax^2 + bx + c = 0\]

has a discriminant \[\Large b^2 - 4ac\]

Answer 2

The discriminant is\[b^2-4ac\]
For reference, the equation for a parabola is \[y=ax^2+bx+c\]

Answer 3

okay, I dunno what to do next @agent0smith

Answer 4

Well, identify what a, b and c are... and plug them into the discriminant.

Answer 5

What? if I take what changed it doesnt fit

Answer 6

If the discriminant is greater than 0, there are 2 real roots. If it is equal to 0, it has 1 real and 1 complex root. If it is less than 0, it has 2 complex roots.

Answer 7

this isn't making any sense to me, I'm sorry I'm not catching on @halorazer

Answer 8

Hmm. I will steal an example from a math website.
in y = 3x² + 9x + 5
You would put the variables in.
a=3
b=9
c=5
Then in the discriminant, which is\[b^2-4ac\]
\[(9)^2-4(3)(5)\]
Then we simplify it.
\[81-60=21\]
Because 21 is greater than zero, there are two real roots. If it was equal to exactly zero, there would be 1 real root and 1 complex one. If it was negative, there would be 2 complex roots.

Answer 9

"What? if I take what changed it doesnt fit"

don't know what this means, but for

x^2 – 2x + 4

a = 1
b = -2
c = 4

Plug them into the discriminant.

Answer 10

x^2 – 2x + 4 = 0 changes to variables. Right? @agent0smith

Answer 11

Just compare it to
ax^2 + bx + c to identify each.

Answer 12

Where did you get a=1?

Answer 13

there's no 1.

Answer 14

What's the coefficient of x^2? It's not zero...

Answer 15

unless you changed x

Answer 16

Ah.

Answer 17

The coefficient of x, or y, or x^2... is 1.

Answer 18

okay, I got a-bx+c????????

Answer 19

@agent0smith ^^

Answer 20

I have no idea what you are doing...

We already know what a, b and c are from above:
a = 1
b = -2
c = 4

Now plug those numbers into \[\Large b^2 - 4ac\]