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#1 2012-12-20 12:01:58
- Frublox
- Novice
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Square root problem
Got this problem on a test:
____
12 + √2x-1 = 4
Okay, so then I subtract 12 from both sides:
____
√2x-1 = -8
2x - 1 = 64 I then square both sides...
2x = 65 Add 1 to each side
x = 65/2 Divide both sides by two.
However, that answer doesn't work. Are there simply no solutions, then?
#2 2012-12-20 13:21:46
- bobbym
- Administrator
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Re: Square root problem
Hi Frublox;
That is correct, there are no solutions. Not every equation is a true statement. You always check the validity of your answer by plugging into the original equation.
Please go here:
http://www.mathsisfun.com/algebra/radic … lving.html
In mathematics, you don't understand things. You just get used to them.
Probability is the most important concept in modern science, especially as nobody has the slightest notion what it means.
90% of mathematicians do not understand 90% of currently published mathematics.
#3 2012-12-20 19:45:43
- bob bundy
- Moderator
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Re: Square root problem
hi Frublox
That answer is the solution to
-12 + √(2x-1) = -4
When you square you cannot help but introduce 'solutions' to this alternative equation as well so you were right to check the value you had.
Bob
You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei
#4 2012-12-20 20:25:17
- anonimnystefy
- Real Member
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Re: Square root problem
Even when you got √2x-1 = -8 you could've said that there are no solutions, because a square root of a positive number is always positive...
The limit operator is just an excuse for doing something you know you can't.
“It's the subject that nobody knows anything about that we can all talk about!” ― Richard Feynman
“A secret's worth depends on the people from whom it must be kept.” ― Carlos Ruiz Zafón
#5 2012-12-20 20:31:14
- bobbym
- Administrator
Online
Re: Square root problem
Hi;
Yes, it always takes the principal value.
In mathematics, you don't understand things. You just get used to them.
Probability is the most important concept in modern science, especially as nobody has the slightest notion what it means.
90% of mathematicians do not understand 90% of currently published mathematics.