Mathematics
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OpenStudy (anonymous):
abs(7x+5)=abs(7x-9)
solve for x
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OpenStudy (anonymous):
abs=absolute value?
OpenStudy (anonymous):
yes gandalf the white
OpenStudy (anonymous):
;)
OpenStudy (anonymous):
I prefer Gandalf the Green... until Ievel up and my profile color changes
OpenStudy (anonymous):
\[\left| 7x+5 \right|=\left| 7x-9 \right|\]
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OpenStudy (anonymous):
thats it but i need x
OpenStudy (anonymous):
I know... working on it...
OpenStudy (anonymous):
sorry, it's been a while... I thought that you had to change all the negative signs to positive and solve. But that doesn't seem to be working :(
OpenStudy (zarkon):
\[\frac{2}{7}\]
OpenStudy (anonymous):
how u solve, zarkon?
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OpenStudy (zarkon):
solve
7x+5=-(7x-9)
OpenStudy (anonymous):
... why? what did u do?
OpenStudy (zarkon):
there are 4 possibilities but only one gives a valid solution
OpenStudy (zarkon):
(7x+5)=(7x-9)
(7x+5)=-(7x-9)
-(7x+5)=(7x-9)
-(7x+5)=-(7x-9)
OpenStudy (zarkon):
I guess 2 give a valid solution
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OpenStudy (anonymous):
how do u know that the others are wrong?
OpenStudy (zarkon):
solve them
OpenStudy (zarkon):
7x+5=7x-9
5=-9
OpenStudy (anonymous):
got it.
OpenStudy (anonymous):
one way to do these is to square both sides:
49x^2 +70x +25 = 49x^2 - 126x + 81
196x = 56
x = 56/196
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OpenStudy (anonymous):
this checks out LHS = 7, RHS = -7 - absolute value 7
OpenStudy (anonymous):
-same as zarkon as 56/186 = 2/7