PSAT 1.10 Math Diagnostic

PSAT 1.10 Math Diagnostic. Which of the following is a factor of the expression?

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Transcript

00:18

potential answer All right so we just tried asking each

00:25

of the answer choices if they were a factor of

00:27

the polynomial But well none of them answered Totally unhelpful

00:31

Thanks guys Tactic number two we figure it out ourselves

00:35

We know that if an expression is the factor of

00:37

a polynomial any roots of the expression must be routes

00:40

of the polynomial And a root of an expression is

00:43

where the expression is equal to zero So if we

00:46

want to test whether an expression is a factor of

00:48

a polynomial we'll have to set it equal to zero

00:51

and then solve for x Well after that we can

00:53

substitute the value we get into the equation And if

00:55

the whole thing ends up peopling zero then the expression

00:59

is a factor or route of the polynomial down confusing

01:03

and let's Just see it in action Going with option

01:05

a x minus two if we set that equal to

01:08

zero i e x minus two equals zero We would

01:11

add to to both sides and get x equals two

01:14

Now we just take our x value and substitute it

01:17

into the original equation We get two cubed minus six

01:21

times two Squared plus five times two plus twelve which

01:26

simplifies to eight minus twenty four plus ten plus well

01:29

and that whole jumbled mess comes out tio six Well

01:33

whether or not it's a master of disguises six is

01:36

no zero so is out We'll try the same thing

01:38

with option b x plus one here will set that

01:41

equal to zero then subtract one from both sides to

01:44

get x equals negative one and we plug in negative

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one for ex well naked one cubed minus six times

01:51

negative one squared plus five times negative one plus twelve

01:55

as we get that all simplifies too negative one minus

02:00

six minus five plus twelve which comes out to wait

02:04

for it Zero that's the face of a winner We

02:07

could do the same for option cnd but since we

02:09

already found the one factor that works there's not really

02:12

any need go further unless we're really starved for entertainment 00:02:15.53 --> [endTime] and maybe invest in an xbox