Question

If a^3-1/a^3=4 then what is the value of a-1/a ??

Answer 1

1 or -0.5±1.9365i

Explanation:

We know that
`x^(3) - y^(3) = (x-y) ^(3) +3xy(x-y)`

So plug in x=a and y=1/a, (a-1/a)^3+3*a*1/a*(a-1/a)=4

Let a-1/a=k, k^3+3k=4, k=1 or a complex conjugate -0.5±1.9365i

That's the answer.