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Mathematics 10 Online
OpenStudy (calculusxy):

Help with quadratic related question... MEDAL!!

OpenStudy (calculusxy):

If I have the solution to a quadratic as \((v + 60)^2 = \sqrt{20}\) then can I simplify this further into \(-6 \pm 2\sqrt{5}\)

OpenStudy (calculusxy):

sorry i meant to say \((v + 6)^2 = \sqrt{20}\)

OpenStudy (calculusxy):

@Nnesha

Nnesha (nnesha):

is that the original question 2sqr{5} is just solution of sqrt{20} how did you get rid of the square root from (v+6)^2

OpenStudy (calculusxy):

i thought that I could just do the inverse to solve for v. and then i put that with the plus/minus and the square root of 20

Nnesha (nnesha):

in order to cancel out the square of (v+6)^2 you have to take square root both sides \[\sqrt{(v+6)^2 } = \sqrt{{2\sqrt{5}}}\]

OpenStudy (calculusxy):

how would i continue doing that?

Nnesha (nnesha):

hmmm is there any statement ? all i can do is just to split it into two equation

OpenStudy (calculusxy):

so do you want the question?

Nnesha (nnesha):

what do you mean ? o.O so (v+6)^2 = sqrt{20} isn't the original question ?

OpenStudy (calculusxy):

no that's like the answer to the question.. i want to know if i can further simplify this.

Nnesha (nnesha):

hmm okay ye i would like to see the original question

OpenStudy (calculusxy):

\(v^2 + 12v + 4 = -2\)

OpenStudy (mathstudent55):

The equation \(x^2 = k\), for non-negative \(k\) has solutions \(x = \sqrt k\) or \(x = -\sqrt {k} \)

Nnesha (nnesha):

and how did you get (v+6)^2 = sqrt{20} ?????? :o

OpenStudy (freckles):

I think you have done something a little off while completing the square

Nnesha (nnesha):

i think you're working on completing the square method :o

Nnesha (nnesha):

ye true :P

OpenStudy (calculusxy):

oh yes sorry about that..

OpenStudy (mathstudent55):

In your case, if you have \((v + 6)^2 = \sqrt{20}\), then the solutions are \(v + 6 = \sqrt{\sqrt{20}}\) or \(v + 6 = -\sqrt{\sqrt{20}}\).

OpenStudy (calculusxy):

i forgot to mention that

Nnesha (nnesha):

and i think ur mistake was \[\rm (x+ \frac{b}{2})^2 \] where we have to take half of the x term and then add (b/2)^2 both sides

OpenStudy (calculusxy):

@mathstudent55 Can't I put \(-6 \pm 2 \sqrt{5}\)

OpenStudy (mathstudent55):

\(v^2 + 12v + 4 = -2\) Subtract 4 from both sides: \(v^2 + 12v = -6\) Now you need to complete the square. Take 12, divide it by 2, and then square it. Add that to both sides. \(v^2 + 12v + 36= -6 + 36\) \(v^2 + 12v + 36= 30\) \((v + 6)^2 = 30\) \(v + 6 = \sqrt {30}\) or \(v + 6 = - \sqrt{30} \) \(v = -6 + \sqrt {30}\) or \(v = -6 - \sqrt{30} \)

OpenStudy (freckles):

you do know that @Nnesha and I are saying that \[v^2 + 12v + 4 = -2 \text{ isn't equivalent to } (v+6)^2=\sqrt{20}\] that you have done something a just a tad bit off in the completing the square process

Nnesha (nnesha):

\(v + 6 = \sqrt{\sqrt{20}}\) or \(v + 6 = -\sqrt{\sqrt{20}}\) this is same as \[\sqrt{(v+6)^2} =\sqrt{2\sqrt{5}}\] but whatever this isn't correct there is a mistake (v+6)^2 =sqrt{20} <--- wrong

OpenStudy (calculusxy):

okay i will correct that but I just need to know how i can simplify it...

OpenStudy (mathstudent55):

I should have this when you complete the square. \((v + 6)^2 = 30\)

OpenStudy (mathstudent55):

Look above at how to get to the correct complete the square form. Then look below that to see how to simplify it and solve the equation.

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