Question

1/a+3-4/a-3=2a/a^2-9

Answer 1

Well it's like :
\[(1/(a+3)) - 4/(a-3) = \] we multiply 1/(a+3) by (a-3), and -4/(a-3) by (a+3), as follow :
\[= (1\times (a-3)/(a+3)\times(a-3)) - (4\times (a+3)/(a-3)\times(a+3))\]
So (a+3)*(a-3) = a^2 - 9
then;
\[= (a-3)/(a^{2} - 9) - (4a+12)/(a^{2} - 9)\]
= \[ = (a - 3 - 4a - 12)/(a^{2} - 9)\]
\[ = (- 3a - 15)/(a^{2} - 9)\]

Answer 2

For future reference, this is better suited to the Math group. Closing this question as off topic.