You can put this solution on YOUR website! Since "b" is inside the absolute value and the absolute value of any number is ALWAYS positive, this means that is ALWAYS positive for any value of "b". So it doesn't matter what the value of "b" is.
What will determine whether is positive or negative is if "a" is positive or negative. So when "a" is positive, then is positive (since multiplying two positive numbers gives you a positive number). When "a" is negative, then is negative (since the product of a negative and a positive number is negative).