Question

You have a 1.7 μf and a 2.2 μf capacitor. what values of capacitance could you get by connecting them in parallel?

Answer 1

You have to add 1.7 and 2.2 together!
1.7+2.2=3.9μF

Answer 2

The effective capacitance of capacitors in parallel is
the sum of the individual capacitances.

The only value of capacitance you could get with
those two in parallel is

                               (1.7 uF + 2.2 uF) = 3.9 uF