x2-81 / x2 times x2-9x / x2+x-90 I cant figure out how this multiplying rational expression is done

x^2-81                  x^2-9x

..........        *          ..........

x^2                        x^2+x-90

To rationalise is to remove any surd expressions from the denominator...

Therefore this is not a 'rationalise the denominator' question

However to work it out you:

1) Factorise the different expressions:

(x+9)(x-9)                   (x-9)(x+0)

...............          *         ...............

(x+0)(x+0)                    (x+10)(x-9)

2) Now you cancel them out:

x+9                      x-9

........         *         ......

x+0                     x+10

3) Finally you times them together to get:

x^2-81

.........

x^2+10

(I am pretty sure this is right, However I acknowledge that I am not the greatest of mathematicians. If you think you see an error please correct me, don't just assume it is right because there is loads written and it looks neat.)

Thanks...

:)

Mathaholic's answer is exactly correct....!!!!