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Mathematics 21 Online
OpenStudy (explainitlikeimfive):

Solve the equation. Identify any extraneous solutions.

OpenStudy (explainitlikeimfive):

OpenStudy (explainitlikeimfive):

A. 6 is a solution to the original equation. The value –5 is an extraneous solution. B. 6 and 5 are both extraneous solutions. C. 5 is a solution to the original equation. The value –6 is an extraneous solution. D. 6 and –5 are solutions.

OpenStudy (dan815):

do u know the meaning of extraneous

OpenStudy (explainitlikeimfive):

That it's unrelated, I think.

OpenStudy (cwrw238):

square both sides x^2 = x+ 30 x^2 -x - 30 = 0 can u solve this?

OpenStudy (explainitlikeimfive):

Ill try

OpenStudy (cwrw238):

extraneous means that although the working out gives it as a solution , it is not possible as a root

OpenStudy (explainitlikeimfive):

5 and 6?

OpenStudy (cwrw238):

not quite (x - 6)(x + 5) = 0 giving x = 6 , -5

OpenStudy (explainitlikeimfive):

So what do I do with that?

OpenStudy (cwrw238):

well see if these roots are possible by substituting each into the original equation

OpenStudy (cwrw238):

eg x = 6 6 = sqrt(6 + 30) 6 = 6 - so that is a genuine root

OpenStudy (explainitlikeimfive):

So I can eliminate B and C

OpenStudy (cwrw238):

yes

OpenStudy (cwrw238):

is -5 a solution?

OpenStudy (explainitlikeimfive):

I dont think so.

OpenStudy (cwrw238):

try plugging in -5 for x in the original equation

OpenStudy (cwrw238):

- 5 = sqrt (-5 + 30) does that work out?

OpenStudy (explainitlikeimfive):

No

OpenStudy (cwrw238):

what are the square roots of 25?

OpenStudy (cwrw238):

5 ANd -5 right?

OpenStudy (explainitlikeimfive):

Yes

OpenStudy (cwrw238):

so its a genuine root

OpenStudy (explainitlikeimfive):

So they're both genuine making them both solutions.

OpenStudy (cwrw238):

right

OpenStudy (explainitlikeimfive):

I do believe I'd pick D

OpenStudy (cwrw238):

correct

OpenStudy (explainitlikeimfive):

Thank you very much.

OpenStudy (cwrw238):

yw

OpenStudy (anonymous):

wrong.

OpenStudy (cwrw238):

please explain why thats wrong

OpenStudy (anonymous):

ask the teacher, I answered D and I got it wrong.

OpenStudy (dan815):

hii

OpenStudy (dan815):

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