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Please help...General question

\sqrt{x^2+40^2}

the same as

{x+40}?

I dont think it is the same, but i dont understand why it is not the same.

@Pangol @RDKGames @Notnek

(edited 6 years ago)

Original post by Dexter212

\sqrt{x^2+40^2}

the same as

{x+40}?

I dont think it is the same, but i dont understand why it is not the same.

@Pangol @RDKGames @Notnek

You're right they're not the same.

If they were the same then

(x+40)^2 = x^2+40^2

. Can you see why this is false?

There is no law for

\sqrt{A+B}

like there is for

\sqrt{AB} = \sqrt{A}\times \sqrt{B}

for example.

Original post by Dexter212

\sqrt{x^2+40^2}

the same as

{x+40}?

I dont think it is the same, but i dont understand why it is not the same.

@Pangol @RDKGames @Notnek

It's not the same, no. The easiest way to see this is to say that if they were equal, you would get the same thing if you squared both of them. If you square the first version, you get x^2 + 40^2. What do you get if you square x + 40 ?

-Mathematician-

You have to work out what’s under the square root first, hence some people put brackets under square root signs. Take root(4+9) as an example. By your logic it would give 2+3 which equals 5. In reality it’s asking for root(13) which is a surd...

Original post by Notnek

If they were the same then

(x+40)^2 = x^2+40^2

. Can you see why this is false?

Great minds...

Original post by Pangol

Great minds...

...do maths.

I suggest putting in some simple numbers. This can help you see that they are not the same:

\sqrt{3^2+4^2} = \sqrt{9+16} = \sqrt{25} = 5

However:

3 + 4 = 7

5 and 7 are different, so this proves that they are not the same.

Original post by Notnek

You're right they're not the same.

If they were the same then

(x+40)^2 = x^2+40^2

. Can you see why this is false?

There is no law for

\sqrt{A+B}

like there is for

\sqrt{AB} = \sqrt{A}\times \sqrt{B}

for example.

So...

\sqrt{x^2+40^2}

is not equal to

\sqrt{x^2}+\sqrt{1600}

?

Original post by joyoustele

So...

\sqrt{x^2+40^2}

is not equal to

\sqrt{x^2}+\sqrt{1600}

?

Correct.

Original post by Notnek

Correct.

Got it, Thanks all. :smile:

:smile:

Original post by joyoustele

Got it, Thanks all. :smile:

:smile:

Are you the OP?

Original post by Notnek

Are you the OP?

Yes.

:smile:

Original post by joyoustele

Yes.

:smile:

Please try to stick to one account so people don't get confused :smile:

:smile:

Original post by Notnek

Please try to stick to one account so people don't get confused :smile:

:smile:

Okay

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