Question 1199801
<pre>
Simplify the following algebraic fraction :
(a^2-3a-4)/(a^2-4) x  (2-a-a^2) /(a^2-1)
answer: (4-a)/(a-2)
how is this worked out ?

What have you tried? Nothing I guess!

{{{((a^2 - 3a - 4)/(a^2 - 4)) * ((2 - a - a^2)/(a^2 - 1))}}}

{{{((a - 4)(a + 1)/(a + 2)(a - 2)) * ((2 + a)(1 - a)/(a + 1)(a - 1))}}} ------ Factoring ALL numerators and denominators

{{{((a - 4)(a + 1)/(a + 2)(a - 2)) * ((2 + a)(- 1)(- 1 + a)/(a + 1)(a - 1))}}} ------ Multiplying 2nd fraction's numerator by - 1 to
                                            match factor in denominator
{{{((a - 4)(a + 1)/(a + 2)(a - 2)) * ((a + 2)(- 1)(a - 1)/(a + 1)(a - 1))}}} 

{{{matrix(1,5, ((a - 4)cross((a + 1))/cross((a + 2))(a - 2)) * (cross((a + 2))(- 1)cross((a - 1))/cross((a + 1))cross((a - 1))), "=",  (- 1)(a - 4)/(a - 2), "=",
highlight(highlight_green(highlight(matrix(1,4, (- a + 4)/(a - 2), ",", or, 
(4 - a)/(a - 2))))))}}}</pre>