Expanding a Square Root

[Jim Dars]

Hi All,

I should point out that I use Mathematica 4.0 infrequently, thus I may be
missing the obvious. My problem is as follows:

In the following I use the square root sign from the palette for SQRT
Expand[(44+9*SQRT(23))^2] yields
3799 + 792*SQRT(23)

I now wish to take the square root of 3799 + 792*SQRT(23) to return to my
original expression. However

Expand[SQRT(3799 + 792*SQRT(23))] merely yields

[SQRT(3799 + 792*SQRT(23))]

What is the proper command to make SQRT(3799 + 792*SQRT(23)) yield
44+9*SQRT(23)

Best wishes, Jim

[Andrzej Kozlowski]

Post by Jim Dars
Hi All,
I should point out that I use Mathematica 4.0 infrequently, thus I may
be
In the following I use the square root sign from the palette for SQRT
Expand[(44+9*SQRT(23))^2] yields
3799 + 792*SQRT(23)
I now wish to take the square root of 3799 + 792*SQRT(23) to return
to my
original expression. However
Expand[SQRT(3799 + 792*SQRT(23))] merely yields
[SQRT(3799 + 792*SQRT(23))]
What is the proper command to make SQRT(3799 + 792*SQRT(23)) yield
44+9*SQRT(23)
Best wishes, Jim

RootReduce[Sqrt[3799 + 792*Sqrt[23]]]


44 + 9*Sqrt[23]

You can of course also use FullSimplify instead of RootReduce but
FullSimplify just calls RootReduce to do the job.

Andrzej Kozlowski


Chiba, Japan
http://www.akikoz.net/~andrzej/
http://www.mimuw.edu.pl/~akoz/

[DrBob]

Post by Jim Dars

Post by Jim Dars
Expand[(44+9*SQRT(23))^2] yields
3799 + 792*SQRT(23)

No, in Mathematica it's

Expand[(44 + 9*Sqrt[23])^2]
3799 + 792*Sqrt[23]

You could do this:

(44 + 9*Sqrt[23])^2
Sqrt[%]

(44 + 9*Sqrt[23])^2
44 + 9*Sqrt[23]

or this:

Expand[(44 + 9*Sqrt[23])^2]
FullSimplify[Sqrt[%]]

3799 + 792*Sqrt[23]
44 + 9*Sqrt[23]

Bobby

Post by Jim Dars
Hi All,
I should point out that I use Mathematica 4.0 infrequently, thus I may be
In the following I use the square root sign from the palette for SQRT
Expand[(44+9*SQRT(23))^2] yields
3799 + 792*SQRT(23)
I now wish to take the square root of 3799 + 792*SQRT(23) to return to my
original expression. However
Expand[SQRT(3799 + 792*SQRT(23))] merely yields
[SQRT(3799 + 792*SQRT(23))]
What is the proper command to make SQRT(3799 + 792*SQRT(23)) yield
44+9*SQRT(23)
Best wishes, Jim

[Jens-Peer Kuska]

Hi,

Sqrt[3799 + 792*Sqrt[23]] // FullSimplify

???

Regards
Jens

Post by Jim Dars
Hi All,
I should point out that I use Mathematica 4.0 infrequently, thus I may be
In the following I use the square root sign from the palette for SQRT
Expand[(44+9*SQRT(23))^2] yields
3799 + 792*SQRT(23)
I now wish to take the square root of 3799 + 792*SQRT(23) to return to my
original expression. However
Expand[SQRT(3799 + 792*SQRT(23))] merely yields
[SQRT(3799 + 792*SQRT(23))]
What is the proper command to make SQRT(3799 + 792*SQRT(23)) yield
44+9*SQRT(23)
Best wishes, Jim