由题意,|2a-1|与(b+2)²互为相反数,
∵互为相反数的两数之和为0,
∴|2a-1|+(b+2)²=0,
又|2a-1|≥0,(b+2)²≥0,
∴2a-1=0,b+2=0,
得a=1/2,b= -2,
ab= -1.