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GED Math 3.5 Graphs and Functions 309 Views


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Description:

GED Math: Graphs and Functions Drill 3, Problem 5. What is the negative root of the quadratic function?


Transcript

00:00

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

00:05

your brought to you by negative roots there Not a

00:08

fan of the latest dye job What's The negative route

00:12

of the quadratic function F of x equals two x

00:15

squared plus nine x minus thirty five And here the

00:18

potential answer All right so this problem wants us to

00:23

find a negative route of a given function All right

00:26

well we should start by factoring the suckers Get it

00:29

its roots All right Well the first thing that shouldn't

00:32

jump out at us is the two coefficient in front

00:34

of our x squared term there Why Well because instead

00:38

of looking for two numbers that multiply to give us

00:40

negative thirty five like we usually would we instead need

00:44

two numbers that multiply to give us negative seventy court

00:48

two times as much to remember Those two numbers need

00:51

tto add up to nine match our middle term narrowing

00:55

our options here Good thing Well we've got ten and

00:59

negative seven or negative Ten and positive seventh but neither

01:04

of those was a nun Well what about negative fourteen

01:08

Five Who Closer Well there's no combination and negative Fourteen

01:11

and five It gives us nine But if we switch

01:14

the minus sign to the other guy while fourteen plus

01:17

negative five totally adds up to nine Now we can

01:20

factor way Start with f ax equals two x squared

01:22

plus fourteen x minus five x minus thirty five and

01:26

new little grouping to get f of x equals two

01:29

acts times the quantity x plus seven minus five times

01:33

the quantity x plus seven Then we factor we explosive

01:36

from both terms and we get f of x equals

01:39

the quantity to x minus five times the quantity x

01:41

plus seven go now it could solve for both routes

01:45

but we only want the negative one here The first

01:48

set of prints sees is going to lead us to

01:49

a positive number so we just zero in on the

01:52

second one and if x plus seven equals zero and

01:56

Acts would equal negative 7 answer choice eh We're pretty

02:00

proud of ourselves for attacking this problem so ruthlessly No

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