Thread: The Quadratic Formula.

Hey there. I am having difficulties with the Quadratic formula,
I know what goes where in the cases, but its just solving from there.
like in this equasion.



2x^2-5x=0



I know how to get it into the quadratic formula
this is what I got.

Originally Posted by facesonfilm

Hey there. I am having difficulties with the Quadratic formula,
I know what goes where in the cases, but its just solving from there.
like in this equasion.



2x^2-5x=0



I know how to get it into the quadratic formula
this is what I got.

that is wrong. c is zero here

I know C is zero there.. but isnt it in the form of Ax^2 + Bx + C?

so then when you plug it into the quadratic formula, you dont input a C.

Originally Posted by facesonfilm

I know C is zero there.. but isnt it in the form of Ax^2 + Bx + C?

so then when you plug it into the quadratic formula, you dont input a C.

you would not have the -4(2) under the square root. since that is -4ac and c is zero

so would the c (which is zero) make the whole 4ac equal zero?

Originally Posted by facesonfilm

so would the c (which is zero) make the whole 4ac equal zero?

umm, yes. zero times any number is zero

Oh kay, I didnt even catch that. Wow.
that sure makes me feel like a genius.
thanks alot!!

I'm surprised no one has pointed out that B is negative meaning that it should be



Since the quadratic is:



Making it

or just

Originally Posted by SnipedYou

I'm surprised no one has pointed out that B is negative meaning that it should be

we would have gotten to that

we just had to deal with a more fundamental error first. anyway, so that we are all clear and on the same page:

the formula is:

here , and

So because I have a negitive with a negitive, it becomes a positive,
even in this case? Correct?

Originally Posted by facesonfilm

So because I have a negitive with a negitive, it becomes a positive,
even in this case? Correct?

yes, the negative of a negative is a positive

okay, I wasn't 100 % on that because our teacher just gave us the formula today like 5 minutes before the bell so I was kinda foggy on that.

why dont you just factorise "2x^2 -5x = 0"

to "x(2x-5) = 0"

then x would have the values:

x = 0 and 2x-5 = 0
2x = 5
x =5/2

Originally Posted by shuggyboi

why dont you just factorise "2x^2 -5x = 0"

to "x(2x-5) = 0"

then x would have the values:

x = 0 and 2x-5 = 0
2x = 5
x =5/2

i think he was required to use the quadratic formula