Define "bigger." Because I have no idea what you mean.
Are you perhaps talking about the modulus of a complex number? The modulus for a complex number a + bi is
(If you were to plot the point representing a complex number on the complex plane, the modulus is also the distance between that point and the origin.)
So plug in the numbers into the expression above to find the moduli (?) of the two complex numbers you have and you can find out which one is "bigger."