# Math Help - simplifying a radical

wolfram|alpha says this is false but doesnt

$\sqrt{36-4x^2} \Rightarrow 2\sqrt{9-x^2}$

trueq[sqrt(36-4x^2) equals 2 Sqrt[9 - x^2]] - Wolfram|Alpha

2. ## Re: simplifying a radical

Originally Posted by Jonroberts74
wolfram|alpha says this is false but doesnt
$\sqrt{36-4x^2} \Rightarrow 2\sqrt{9-x^2}$
trueq[sqrt(36-4x^2) equals 2 Sqrt[9 - x^2]] - Wolfram|Alpha
On the other hand, look at this.

And this.

4. ## Re: simplifying a radical

why would it state it as false? Because, something subtracting something it equals is zero.

5. ## Re: simplifying a radical

And yet again. Obviously "trueq" is a bit titchy. Always trust your mind over a computer.

-Dan

6. ## Re: simplifying a radical

Originally Posted by Jonroberts74
why would it state it as false? Because, something subtracting something it equals is zero.
Because no computer algebra system is flawless.
You may be miss-using the "is equal" operation. Although, I have never seen that operation. So I have no idea how to answer your doubt.