Question

Radical x^2 + 21 = 2X

Answer 1

\[\sqrt{x^2+21} = 2x ~~ ?\]

Answer 2

Yes!

Answer 3

Square both sides first to get rid of the radical.

Answer 4

X^2 + 21 = 4x^2?

Answer 5

correct. subtract x^2 from both sides to isolate x.

Answer 6

4x=21?

Answer 7

Subtract x^2 from both sides:
x^2 + 21 = 4x^2
-x^2 -x^2
-------------------
? = ?
--------------------

Answer 8

X+21=4?

Answer 9

No. You have one x-square on the left and you have four x-square on the right.
If you subtract one x-square from both sides you will have:
zero x-square on the left and three x-square on the right.
21 = 3x^2

Answer 10

Ohh okay!

Answer 11

divide both sides by 3 and then take the square root on both sides to solve for x.

Answer 12

2.645751311

Answer 13

I would leave the answer as a square root of a number rather than decimals.

Answer 14

Okay thank you so much!

Answer 15

You are welcome. \(x = \sqrt{7}\)