Question 1031469
Sorry, I do not have square sign on my keyboard.                    
<pre><font size = 4><b>
Yes you do. Hold down the Alt key while typing 253 on
the keypad at the far right of your keyboard (not the
number keys above the letter keys).  When you let up
the Alt key after typing 253 on the keypad suddenly ² 
will come up on the screen.  For cubes ³ use 0179.

{{{-expr(3/4)a - expr(2/3)a^2+expr(3/5)a}}}

Get a common denominator of 60

{{{-expr(45/60)a - expr(40/60)a^2+expr(36/60)a}}}

{{{-expr(9/60)a - expr(40/60)a^2}}}

{{{expr(-a/60)(9+40a)}}}

Edwin</pre></b></font>