I don't know how to do quadratic equasions! Please help!?

Question

I have a maths exam today! Please help! Quadratic equasions and parabolas!

Answer 1

The consistent way to solve a quadratic equation.

1. Get all terms over to the left, so that you have a formula of the style ax^2 + bx + c = 0

2. Solve like this

x = (-b +/- sqrt(b^2 - 4 * a * c))/(2 * a)

For example:

x^2 + 11x - 12 = 0

a = 1
b = 11
c = -12

x = (-11 +/- sqrt(11^2 - 4 * 1 * -12))/(2 * 1)
x = (-11 +/- sqrt (121 + 48))/2
x = (-11 +/- sqrt(169))/2
x = (-11 +/- 13)/2
x = (-11 + 13)/2 or (-11 - 13)/2
x = 2/2 or -24/2
x = 1 or -12

Answer 2

It would have helped to be more specific, but I'll just have to explain the entire thing.
Quadratic equations are in a form like this:
ax^2+bx+c
The equation can be factored and made into a form like this:
(d+x)(e+x)
The quadratic formula for finding roots of x or values of x that give you 0's is:
[-b+/-(b^2-4ac)^1/2]/2
Just plug in the a value of the equation, the b value, and the c value and you should get a value for x that will make you have a 0.
I find this method also useful for factoring.
Sometime I would be given x^2+5x+6=12
I know that the equation does not equal 0, but I would pretty much find an x value from the quadratic equation. Then you would subtract the x value you get by a number so you can get a 0. For instance if you used the quadratic formula and got x as 6. You subtract x by 6. If your second value of x is 5, you subtract by 5.
So you would get (x-6)(x-5) OKAY, back to the equation I gave you back up there.
If you used the quadratic equation x would have 2 values. Either -2 or -3.
(x+2)(x+3)=12
Parabolas are just curves that aare graphed by quadratic equations. If you plug an x value in, you can get a y value out.
the vertex is at (-b/2a,f(-b/2a)) f(x) is y meaning you plug -b/2a into the function to get a y value for the vertex.

Answer 3

Quadractic equations are solved when you have

ax^2+bx+c (sometimes you have to put it in this form)

it helps me if I write

a=?, b=?, c=?

Tip: When there is no number in front of the a, b, or c it is always 1

The Quadratic formula is

-b plus or minus the square root of b-4ac all divided by 2a

It can't really be written out so that you can see it.

What helped me to memorize this is to write the equation before each and every problem above my homework...

I hope this helps.

Answer 4

x = the opposite of b plus or minus the square root of b squared minus 4(a)(c) all divided by 2a

x = (-b +/- (square root: b^2 - 4(a)(c))) / 2a

Where a, b, and c...

ax^2 + bx + c = 0

Hope it helps, though with an exam today, I dunno how you'll master it... good luck, I suppose.