Okay. I have this problem that I have solved several times. I keep getting the same answer, but when I plug it in it is wrong. What am I doing wrong?

2x^(2)-5x=7

x^(2)-(5/2)x=(7/2)

x^(2)-(5/2)x+(25/16)=(7/2)+(25/16)

(x-(5/2))^(2)=(81/16)

x-(5/2)=(+/-)(9/4)=(5/2)

final answer: (19/4) or (1/4)