To find sin(2x), first square the given equation sin(x) + cos(x) = 5/4:

(sin(x) + cos(x))^2 = (5/4)^2
sin^2(x) + 2sin(x)cos(x) + cos^2(x) = 25/16
(sin^2(x) + cos^2(x)) + 2sin(x)cos(x) = 25/16
1 + 2sin(x)cos(x) = 25/16
2sin(x)cos(x) = 25/16 - 1
2sin(x)cos(x) = 9/16

Now, use the double angle identity sin(2x) = 2sin(x)cos(x):

sin(2x) = 2sin(x)cos(x)
sin(2x) = 2 * (9/16)
sin(2x) = 18/16
sin(2x) = 9/8

Therefore, sin(2x) = 9/8.