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# The Quadratic Formula- How it works

A quick presentation that teaches you how to use and understand the Quadratic Formula.

by

Tweet## Silas Wright

on 26 September 2012#### Transcript of The Quadratic Formula- How it works

The Quadratic Formula ax^2+bx+c=0 You hate seeing that,

don't you? You hate seeing

these equations I don't mean to annoy you Well, that's just too bad If

you're

like

me That

sentence

scared

you But help you! Factoring trinomials can be hard It involves

thinking of a bunch

of numbers, that may

or may not fit! For example

x^2+4x-45 Ok....

numbers that

factor into 45

that can add or

subtract to equal

Positive 4.... Too much thinking There is a

FORMULA

that makes no

extra thinking! No Joke Its called the

Quadratic Formula Stay with me here! It will make sense That was the formula to

help you factor trinomials And Here is how you use it x^2+4x-45 Let's look at that Trinomial again ax^2+bx+c=0 I want you to look at that trinomial

(and any others) Like this ax^2+bx+c=(1)x^2+4x-45 So now find a, b, and c. So you can replace "a" with 1

"b" with 4

and "c" with -45 Do you

realize how

I found

that? So now lets go back to

the Quadratic formula Now you just have to take that,

and plug in the "a", "b", and "c" Now you can just simplify the equation Keep on simplifying Now we have to do two different steps we add the top part together That gets us (x=5) But we also have to subtract the top part That leaves (x=-9) So now we have

(x=5) and (x=-9) Now since ax^2+bx+c=0

We have to take

(x=5) and (x=-9)

and make then equal

to zero So to make (x=5) equal to zero,

it ends up as x-5=0

(and then (x=-9) is x+9=0) And now we have

(x-5) and (x+9)

Notice anything about that? (x-5)(x+9)

This is what your

factored trinomial

looks like!! That's how

to use the quadratic

formula Lets

recap First get your

trinomial,

and find your

"a", "b", and "c" Then Plug

it into the

Quadratic

Formula Then Simplify until you

get your

results And that was

how to use...

Full transcriptdon't you? You hate seeing

these equations I don't mean to annoy you Well, that's just too bad If

you're

like

me That

sentence

scared

you But help you! Factoring trinomials can be hard It involves

thinking of a bunch

of numbers, that may

or may not fit! For example

x^2+4x-45 Ok....

numbers that

factor into 45

that can add or

subtract to equal

Positive 4.... Too much thinking There is a

FORMULA

that makes no

extra thinking! No Joke Its called the

Quadratic Formula Stay with me here! It will make sense That was the formula to

help you factor trinomials And Here is how you use it x^2+4x-45 Let's look at that Trinomial again ax^2+bx+c=0 I want you to look at that trinomial

(and any others) Like this ax^2+bx+c=(1)x^2+4x-45 So now find a, b, and c. So you can replace "a" with 1

"b" with 4

and "c" with -45 Do you

realize how

I found

that? So now lets go back to

the Quadratic formula Now you just have to take that,

and plug in the "a", "b", and "c" Now you can just simplify the equation Keep on simplifying Now we have to do two different steps we add the top part together That gets us (x=5) But we also have to subtract the top part That leaves (x=-9) So now we have

(x=5) and (x=-9) Now since ax^2+bx+c=0

We have to take

(x=5) and (x=-9)

and make then equal

to zero So to make (x=5) equal to zero,

it ends up as x-5=0

(and then (x=-9) is x+9=0) And now we have

(x-5) and (x+9)

Notice anything about that? (x-5)(x+9)

This is what your

factored trinomial

looks like!! That's how

to use the quadratic

formula Lets

recap First get your

trinomial,

and find your

"a", "b", and "c" Then Plug

it into the

Quadratic

Formula Then Simplify until you

get your

results And that was

how to use...