Question

Solve the equation: (RADICALS PLZ HELP)

Answer 1

What is the equation

Answer 2

\[\sqrt{2x+15}-x=6\]

Answer 3

I got the answer, I just dont know how lol

Answer 4

what did you get as your answer?

Answer 5

-3

Answer 6

the choices are {-7}, O with a line through it, {-3}, and {-7,-3}

Answer 7

\[\sqrt{2x +15}-x =6\]
\[(\sqrt{2x+15})^{2}=(6 + x)^{2}\]
\[2x + 15 = x ^{2} + 12x + 36\]
\[x ^{2}+10x +21 = 0\]
\[(x+3)(x+7) =0 \]
x = -3, x = -7

Answer 8

You didn't really tell us what step you don't understand.
I'm guess the radical step?
\[\sqrt{x}\] is the same as \[(x)^{\frac{ 1 }{ 2 }}\]
So, you can think of it as:
\[(2x+15)^{\frac{ 1 }{ 2 }}\]
\[(2x+15)^{\frac{ 2 }{ 2 }}\]
\[(2x+15)^{1}\]

and remember what you do to one side of the equation, you must do it on the other side as well.

Answer 9

The thing is, on mathway it says that in this case, -7 was proven invalid @StarJ9

Answer 10

What was the whole question?

Answer 11

That was the whole euqation!

Answer 12

question!* It simply said to solve

Answer 13

I don't understand the second thing you put? Sorry and thanks for your patience!!!!

Answer 14

You have two sets of x points, (-3, 0) and (-7,0)
Plug in one x value and see if your equation = 6.
This is why -7 does not work.

Answer 15

OMG YES!! THANK YOU lol

Answer 16

But why did it become negative?

Answer 17

It went from (x+3)(x+7)=0 to x=-3 and x=-7

Answer 18

You just answered your own question ^

Answer 19

x + 3 =0, x+3 - 3 = 0-3

Answer 20

I did? Wait why did you subtract 3?!

Answer 21

I think I get it now.... Lol we had to remove the parenthesis huh

Answer 22

\[x + 3 = 0\]
\[x + 3 -3 = 0 -3\]
\[x = -3\]
I subtract 3 from both sides to get x by itself

Answer 23

WAIT omg im sorry but when you said "Plug in one x value and see if your equation = 6.
This is why -7 does not work." we plug into the original equation right?

Answer 24

Yes!

Answer 25

Yaaayyy -.- Lol thanks!

Answer 26

\[\sqrt{2(-3) + 15} -(-3) =6\]