Mathematica Can someone tell me the commands of these in Mathematica/Wolframalpha?

[flyingpig]

Alright I have been trying to figure out these commands for the past month and I could not get them. Hopefully one of you could lead me to it

Multiple Integrals in Polar Coordinates

Here is an example

Integrate[r, {r, 1, sqrt(2sin(2*theta))}, {theta, pi/12, 5pi/12}]

I typed this in and I get

[PLAIN]http://www3.wolframalpha.com/Calculate/MSP/MSP135219f87b7148ah12d000004fca37i7cda808h9?MSPStoreType=image/gif&s=25&w=291&h=50

It does not give me a numerical answer

Row Operations with Elementary steps

I don't even know how to get this. I can get the rref(M) of a matrix M, but that's pretty much it...

I like to know the commands for echelon form

Leave the final answer in rref(A) without factoring

Let's say I have a matrix \begin{bmatrix}<br /> 1 &amp; 5 &amp; 7\\ <br /> 1&amp; -2 &amp;-2 <br /> \end{bmatrix}

I punch this into Wolframalpha using RowReduce{{1,5,7},{1,-2,-2}} and I get

[PLAIN]http://www4d.wolframalpha.com/Calculate/MSP/MSP30119f87cg4dgd3fi1h00005c11c2c4cc7d2i70?MSPStoreType=image/gif&s=60&w=76&h=36

See how they factor the 7 out? How do you make it so that it DOESN'T do that?

Leave answers in decimal in matrix

Pretty much the opposite of what is requested from before.

 

[ChristinaJ]

Use //N at the end of a line in Mathematica to give a decimal output.

I'm not sure about Wolfram Alpha.