math F4

x+y=26...1
(x.y)/2=120...2
x.y=240...3
what are the x and y?
Sol
x+y=26
y=26－x
xy=240
x(26－x)=240
26x－x^2=240
x^2－26x+240=0
x=(26+/-√(26^2－4*1*240))/2
=(26+/-√(－284))/2
=(26+/-2i√71)/2
=13+/-i√71
(1)x=13+i√71 =>y=13－i√71
(2)x=13－i√71 =>y=13+i√71