How do you add or subtract #(y^2-5)/(y^4-81) + 4/(81-y^4)#?
We can rewrite this sum as
We can find the lowest common denominator, which, then, is
Using the l.c.d.:
That can be your final answer, but let's draw attention to the fact we have factorable functions there.
Let's find the roots of
Now, as for the denominator:
Let's just go slowly here and take the square root of both sides.
So, here, as we are dealing with a polinomial of 4
Therefore, your "final" answer can be rewritten as
Finalfinal answer, then: