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Mathematics 8 Online
OpenStudy (saifoo.khan):

Help needed! Big time.

OpenStudy (anonymous):

with?

OpenStudy (saifoo.khan):

\[\frac{\sqrt{4y+2}+13}{6} =2\]

OpenStudy (aravindg):

all izz well !

OpenStudy (saifoo.khan):

y = -1/4. Now someone verify it for me.

hartnn (hartnn):

whats your progress/attempt ?

OpenStudy (saifoo.khan):

Show steps.

hartnn (hartnn):

no, y=-1/4 isn't correct, 14/6 is not 2

OpenStudy (saifoo.khan):

OpenStudy (aravindg):

i am gettng no solution exist :O

terenzreignz (terenzreignz):

Unless it be imaginary matey :D

hartnn (hartnn):

when you squared both sides, you attached an extra root y=-1/4

OpenStudy (saifoo.khan):

Where?

hartnn (hartnn):

yeah, answer to this is imaginary, or if we talk in real number terms, there's no solution

hartnn (hartnn):

(root (...))^2 = (-1)^2

OpenStudy (aravindg):

obviously 12-13=-1 .. that would mean you are going for imaginary !!

terenzreignz (terenzreignz):

Wait, not imaginary... more like nonexistent, as @AravindG said... I'm missing something, but I'm sure \[\sqrt{x}=-1\] has no solution

OpenStudy (saifoo.khan):

I'm confused.

OpenStudy (aravindg):

i is defined as \[i^2=-1\]

terenzreignz (terenzreignz):

Don't we always consider the positive square root?

terenzreignz (terenzreignz):

I mean, sure, i is a solution to \[\large x^2=-1\] but \[\large \sqrt{x}=-1\] ?

OpenStudy (aravindg):

@terenzreignz yes but we can get imaginary number for positive root also

OpenStudy (saifoo.khan):

The answer is {} though

OpenStudy (aravindg):

\[\sqrt{x}=i\]

hartnn (hartnn):

oh , yes, here there no solution, not even imaginary. from \(\sqrt{4y+2}=-1\) you can directly say no solution or {}

OpenStudy (aravindg):

as i said in my first statement

terenzreignz (terenzreignz):

{} --> no solution exists.

OpenStudy (saifoo.khan):

BUT when we verify: [sqrt(4*-1/4 + 2) + 13 ]/6 [sqrt(-1 + 2) + 13 ]/6 [sqrt(1) + 13 ]/6 14/6 7/3

terenzreignz (terenzreignz):

wolf does consider complex numbers right? So even in Complex Numbers, no solution exists?

hartnn (hartnn):

yeah, its 7/3, not 2

OpenStudy (aravindg):

\[\dfrac{7}{3} \neq 2\]

hartnn (hartnn):

yes, no solution even in complex numbers

OpenStudy (aravindg):

so no solution

OpenStudy (saifoo.khan):

[sqrt(4*-1/4 + 2) + 13 ]/6 [sqrt(-1 + 2) + 13 ]/6 [sqrt(1) + 13 ]/6 14/6 or (-1+13)/6 < this bothers me. 7/3

hartnn (hartnn):

sqrt 1 is never -1

terenzreignz (terenzreignz):

Because we always consider the square root to be the principal square root, or else the square root is not a well-defined function.

OpenStudy (aravindg):

yaa !!

OpenStudy (aravindg):

you are considering positive square root

OpenStudy (saifoo.khan):

Why so? When sqrt9 = +-3, so why can't this be?

hartnn (hartnn):

no, sqrt 9 is just 3

OpenStudy (aravindg):

noo sqrt 9 not equal to +-3

OpenStudy (saifoo.khan):

D:

hartnn (hartnn):

square roots have only one root

OpenStudy (saifoo.khan):

Then what thing have 2 roots?

hartnn (hartnn):

quadratic equations have 2 roots

terenzreignz (terenzreignz):

Uh'oh a philosophical discussion coming up... :D While it is true that +/- 3 is a solution to the equation \[\large x^2 - 9 = 0\] only 3 is a solution to the equation \[\large x=\sqrt{9}\]

hartnn (hartnn):

^ yes

terenzreignz (terenzreignz):

Sorry, it makes more sense if written as \[\large x^2 = 9\]

OpenStudy (aravindg):

9 has two square roots a positive square root and a negative square root when we usually speak of square root we talk about positive square root ie \[\sqrt{9}, -\sqrt{9}\] are square root of 9

OpenStudy (aravindg):

see that always a quantity under root is positive

OpenStudy (saifoo.khan):

Why me no get it?

OpenStudy (aravindg):

because it is a common misconception from childhood !!

OpenStudy (aravindg):

believe me i had the same problem 2 years before!

OpenStudy (saifoo.khan):

So we will just have one answer?

OpenStudy (saifoo.khan):

I mean 1 solution?

terenzreignz (terenzreignz):

Oh, I seem to recall my teacher telling us that a way to define the absolute value for real numbers... \[\large |x|=\sqrt{x^2}\]

terenzreignz (terenzreignz):

Which would not make sense if the square root could be negative.

OpenStudy (aravindg):

exactly !!!

OpenStudy (aravindg):

really worth checking out :: http://en.wikipedia.org/wiki/Square_root

OpenStudy (aravindg):

unless specified we always talk of principal square root

OpenStudy (saifoo.khan):

Hmm. I guess i get it. Thanks @AravindG @hartnn @terenzreignz

hartnn (hartnn):

be careful next time :)

OpenStudy (saifoo.khan):

*Hope so* :D

OpenStudy (aravindg):

as @terenzreignz stated :)

terenzreignz (terenzreignz):

:) \[\huge \sqrt{x} \ \ge \ 0\]

hartnn (hartnn):

its actually \(\sqrt{x^2}=|x|\) and not \(\sqrt{x}=|x|\)

OpenStudy (saifoo.khan):

Lol.

OpenStudy (aravindg):

oopsie i made a blunder there ..thanks for pointing out

OpenStudy (anonymous):

it means this question is wrong

sam (.sam.):

lol

OpenStudy (ryan123345):

|dw:1365814919544:dw| Haha I love my neat work :3

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