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TSI Math: Solving a Quadratic Equation for x 5 Views


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Description:

What is x for the equation 2x² + 36 = -18x?


Transcript

00:03

Okay sy mash members next on our little quadratic friendly

00:07

exploration tour Here What is acts for the equation to

00:11

x squared plus thirty six equals negative eighteen x So

00:17

when we're solving a quadratic equation always start by setting

00:20

one side of the equation over here and then we're

00:23

going to put the zero thing he over here right

00:25

So it might help to pretend that we're kali's hurting

00:28

the terms to the left side like sheep And we're

00:31

adding eighteen acts to both sides there See if we

00:34

do that we get to x squared plus eighteen ax

00:36

plus thirty six equal zero Okay Since each term of

00:40

this quadratic is divisible by two well let's divide both

00:43

sides of the equation by two to simplify the factoring

00:45

process knows that the right side remains equal to zero

00:48

since zero Divided by two in california is zero so

00:51

we get x squared plus nine x plus eighteen Now

00:54

we need two factors of the constant term eighteen that

00:57

add up to the ex coefficient nine what are they

01:00

Well what times What is eighteen Well could it be

01:02

two and nine Yes but it's not one in eighteen

01:05

Yes but it's not And yes it's three and six

01:08

and conveniently three plus six is nine So it looks

01:12

like that explosive six and then explodes three zero Well

01:15

the final staff is set Each factor equals zero and

01:17

salt for acts right So if x plus six zero

01:20

than x cast to be a minus six And similarly

01:22

three has to be minus three They're the solution given

01:25

Equation is x equals negative six comma negative three and

01:30

that's it The answer is b and don't get fooled

01:32

by the others because they all use the wrong factors

01:35

to get eighteen and other mistakes like that So answer

01:38

is b but but

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