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Mathematics 15 Online
OpenStudy (seratul):

Algebra Help

OpenStudy (seratul):

\[\sqrt{x+5}-x=-1\]

OpenStudy (seratul):

I know that you first add x on each side. You get \[\sqrt{x+5}=x-1\]

satellite73 (satellite73):

square now

OpenStudy (seratul):

Then you square to get \[x+5=x^2-2x+1\]

OpenStudy (seratul):

subtract one\[3x+4=x^2\] and add 2x on both sides

OpenStudy (seratul):

Now I don't know.

OpenStudy (3mar):

If I may help?

OpenStudy (seratul):

Anyone is welcome to help lol. Please

OpenStudy (3mar):

Are you familiar with the quadratic formula?

OpenStudy (seratul):

Oh, of course... Alright, I think I know how to do it now. Thanks!

OpenStudy (3mar):

Any Help... Any Time... If you want me to walk with you through it, I don't mind

OpenStudy (seratul):

Is it alright if I quickly solve and ask if it's correct?

OpenStudy (3mar):

Yes, No problem.

OpenStudy (seratul):

Okay, I got x=4 and x=-1 It can't be -1 cause the equation would be false, so it's x=4.

OpenStudy (3mar):

You mean: \[x^2-3x+4=0\] \[(x-4)(x+1)=0\]??

OpenStudy (seratul):

Yea. So x would be 4 or -1

OpenStudy (seratul):

And if I plug back in, only 4 works.

OpenStudy (3mar):

I don't think so! Let me show it to you if you don't mind.

OpenStudy (seratul):

You made a mistake, it should be x^2-3x-4.

OpenStudy (3mar):

a=1 b=-3 c=4 Direct substitution will lead to two imaginary conjugates:\[\frac{ 3 }{ 2 }+\frac{ \sqrt{7} }{ 2 }i\] and \[\frac{ 3 }{ 2 }-\frac{ \sqrt{7} }{ 2 }i\]

OpenStudy (seratul):

c is -4

OpenStudy (3mar):

Sorry It would be easier now (x+1)(x-4)=0 but why did you exclude -1?

OpenStudy (seratul):

If you plug in -1 to the original equation, you would get 3=-1 which is not true So x=-1 cannot be an equation.

OpenStudy (3mar):

How "you would get 3=-" \[x^2-3x-4=(-1)^2-3(-1)-4=1+3-4=0\] It is correct and satisfy the original equation!

OpenStudy (seratul):

That isn't the original equation. Look all the way at the top :P

OpenStudy (seratul):

-1 only satisfies the quadratic equation.

OpenStudy (seratul):

Anyways, thanks for the help :D I extremely appreciate it.

OpenStudy (3mar):

I thank you that you gave me that chance to help you!

OpenStudy (3mar):

Thank you for the medals!

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