Solve and check for extraneous solutions
16=3(x-1)-(x-7)
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OpenStudy (anonymous):
@satellite73
OpenStudy (anonymous):
not sure what "extraneous" solutions means in this context
it is a linear equation right? no radials, no denominators
OpenStudy (anonymous):
distribute first on the right both the 3 and the minus sign
OpenStudy (anonymous):
let me know what you get
OpenStudy (anonymous):
Ok, so I got 2x+6=16
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OpenStudy (anonymous):
think there is a mistake there
the \(2x\) is right, but where did the \(6\) come from?
OpenStudy (anonymous):
-1+7
OpenStudy (anonymous):
\[3(x-1)-(x-7)=3x-3-x+7\] is a start
OpenStudy (anonymous):
oops forgot the distributive law didn't you?
OpenStudy (anonymous):
\[3(x-1)=3x-3\times 1\]
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OpenStudy (anonymous):
Oh okay! So 2x+4?
OpenStudy (anonymous):
right
\[2x+4=16\] takes only 2 steps to solve
OpenStudy (anonymous):
a) subtract 4
b) divide by 2
OpenStudy (anonymous):
2x=10
x=2
OpenStudy (anonymous):
???
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OpenStudy (anonymous):
first off \(16-4\neq 10\) and secondly \(\frac{10}{2}\neq 2\) so both steps are wrong
OpenStudy (anonymous):
what is \(16-4\)?
OpenStudy (anonymous):
16-4=12
OpenStudy (anonymous):
ok so
\[2x+4=16\\
2x=12\] is a the first step
OpenStudy (anonymous):
x=6! So sorry, it's late where I am lol so I have a sleepy brain I suppose
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OpenStudy (anonymous):
second step is \(x=\frac{12}{2}\)
OpenStudy (anonymous):
x=6
OpenStudy (anonymous):
right
OpenStudy (anonymous):
How do we check for extraneous solutions?
OpenStudy (anonymous):
there are no extraneous solutions with linear equations, nothing to check
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OpenStudy (anonymous):
you can replace x by 6 in the original equation and see that it works if you like but it is right, nothing is extraneous here
OpenStudy (anonymous):
ok:) Can I ask another? I'll be better haha
OpenStudy (anonymous):
sure
OpenStudy (anonymous):
x/3=x/2-2
Check for extraneous solutions
OpenStudy (anonymous):
is this
\[\frac{x}{3}=\frac{x}{2}-2\] like that ?
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OpenStudy (anonymous):
yup
OpenStudy (anonymous):
you have a choice
you can work with the fractions or you can get rid of them
OpenStudy (anonymous):
you pick
OpenStudy (anonymous):
get rid of them.
OpenStudy (anonymous):
Actually, which ever is simpler
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OpenStudy (anonymous):
then since the least common multiple of 2 and 3 is 6, if you multiply both sides by 6 they will be gone
most people i think like getting rid of fractions
OpenStudy (anonymous):
\[6\times \frac{x}{3}=6\times (\frac{x}{2}-2)\]
OpenStudy (anonymous):
I think I did it wrong bc I got 2x/6-3x/6
OpenStudy (anonymous):
since \(\frac{6}{2}=3\) and \(\frac{x}{3}=2\) you end up with
\[2x=3x-18\]
OpenStudy (anonymous):
you forgot to get rid of the 6 when you cancelled
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OpenStudy (anonymous):
oh okay:)
OpenStudy (anonymous):
\[6\times \frac{x}{3}=2x\] not \(\frac{2x}{6}\)
OpenStudy (anonymous):
so now you have
\[2x=3x-18\] which takes 2 steps to solve
you see where the \(-18\) came from?
OpenStudy (anonymous):
Yes!
OpenStudy (anonymous):
x=18
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