Solve the equation. Identify any extraneous solutions.
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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?
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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?
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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?
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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?
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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
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OpenStudy (explainitlikeimfive):
I do believe I'd pick D
OpenStudy (cwrw238):
correct
OpenStudy (explainitlikeimfive):
Thank you very much.
OpenStudy (cwrw238):
yw
OpenStudy (anonymous):
wrong.
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