I have to do this question without a calculator.Let A= . Then what is the value of ?

a) -17

b) x 17

c)

d) -24

I could work it out doing lots of multiplication but this question is taken off a test where we have to do 11 questions in an hour. There must be a shorter way of doing it.

Here was another way I was thinking of:

The disciminant is

I can see that the 17 from the choices is appearing but since it's then i'm going to get a in my answer somewhere.

Can anyone help?