# This is adding ad subtracting rational expression (dissimilar) 2 over a+3 - (minus) 4 over a-3 please i really need it right now

1
by hiplzhelpmemath

2015-10-04T18:13:53+08:00
2                 4
a + 3           a - 3

Factor the denominators. (The given denominators are already on their factored form so we'll just copy them).
a + 3 = a + 3
a - 3 = a - 3

Let's construct their LCD.
LCD = (a + 3)(a - 3)

Rewrite each rational expression with the LCD as denominator.
2                 4        =       2 (a - 3)               4 (a + 3)
a + 3           a - 3          (a + 3)(a - 3)         (a + 3)(a - 3)

We get 2(a - 3) and 4(a + 3) from dividing the LCD to their factored denominators then multiply them to their numerator.
(a + 3)(a - 3)   =   a - 3
a + 3

(a + 3)(a - 3)   =   a + 3
a - 3

Now do the indicated operation.
2 (a - 3)   -     4 (a + 3)      =      2 - 4
(a + 3)(a - 3)                          1
=      -2
1
=    -2

That's it. Hope you understand it! :)
-KookEin
Note: It's not copied :)