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Description:

GED Math: Expression and Equations Drill 3, Problem 4. What are the roots of the quadratic equation?

Language:
English Language

Transcript

00:00

Thank you We sneak in and here's your smoke to

00:05

your brought to you by the golden rule which is

00:08

basically don't ever try to take a leper con school

00:11

Really not worth getting away from my goal All right

00:14

one of the routes of the quadratic equation x squared

00:16

plus seven x minus thirty equals forty eight and hear

00:19

the potential answers it is All right very matthew question

00:28

here We need to solve this quadratic x squared plus

00:32

seven x minus thirty equals forty eight and figure out

00:35

what the roots would be All right Well here's the

00:37

golden rule first solving quadratic always said one side of

00:40

the equation equal to zero before trying to factor well

00:44

to get one side to be zero We're going to

00:46

need to subtract forty eight from both sides and just

00:49

rewrite The equation is x squared plus seven x minus

00:51

seventy eight equals zero and now we need to get

00:55

two factors of negative seventy eight that add up to

00:57

seven Like what Times what would be seventy eight But

01:02

then if you also added to the seven and we

01:04

could start thinking well alright we think it could be

01:06

like thirty nine times to could it be three times

01:10

thirteen and no that's It can't break down thirteen any

01:15

further So the factors are two three and thirteen is

01:21

any combination of those make seven So the answer is

01:24

no not really But if we multiply the two and

01:27

the three together we get six and six from thirteen

01:32

is seven We need this To be negative seventy eight

01:35

So we'll have tohave one minus sign in there when

01:38

we're factoring and we're gonna wind up with x minus

01:41

six times x plus thirteen that if we multiplied check

01:46

ourselves except axes x squared than outside him outside his

01:50

x times thirteen thirteen x minus six x yeah thirteen

01:54

minus six is seven and then negative six times thirteen

01:57

Yep that gets us our negative seventy eight But now

02:00

that we're done factoring one of the routes well x

02:03

minus six zero so one factor has got to be

02:05

six and x plus thirteen's gotta be zero so yep

02:10

negative thirteen is the other one so our answers eh

02:14

You can have the answer but don't touch my gold

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