Thực hiện các phép tính :
a) \(\left(2+3i\right)\left(3-i\right)+\left(2-3i\right)\left(3+i\right)\)
b) \(\dfrac{2+i\sqrt{2}}{1-i\sqrt{2}}+\dfrac{1+i\sqrt{2}}{2-i\sqrt{2}}\)
c) \(\dfrac{\left(1+i\right)\left(2+i\right)}{2-i}+\dfrac{\left(1+i\right)\left(2-i\right)}{2+i}\)