x+2=5+a
x=a+3
1+x=3a
x=3a-1
a+3=3a-1
3a-a=3+1
2a=4
a=2
a²-2a+2010
=a²-2a+1+2009
=(a-1)²+2009
=(2-1)²+2009
=2009+1
=2010