f(x)=x-1 /x-1 =1 when x is positive or 0 and doesnot =1
f(x)= x-1 /-x-1 when x is negative anot= -1
f(1)=1=lim f(x)as x tends to1 so a=1
lim f(x) as x to -1 from right= +infinity
limf(x) as x tends to -1 from left =-infinity
so lim f(x) as x tends to -1 does not exist
then f is not continuous at x=-1
so we can not compute a value for b