小李在电脑中设置了一个有理数的运算程序,输入数a,输入*键,再输入b,得到运算a*b=a2-2(3a-1/b)÷(a-b

(-1/2)²-2[3(-1/2)-1/2]÷[(-1/2)-2]
=1/4-2×-2÷(-5/2)
=1/4+4×(-2/5)
=1/4-8/5
=5/20-32/5
=-27/5