(a) negative (b) positive (c) positive (d) negative
Work Step by Step
(a) Since a is positive, -a is negative. (b) Since b and c are both negative, bc is positive. (c) Since a is positive and b is negative, a-b is positive (subtracting a negative number reverses the sign and this essentially becomes the sum of two positive numbers, which is positive). (d) Since a is positive and b is negative, ab is negative. Similarly, since a is positive and c is negative, ac is negative. Thus ab + ac becomes the sum of two negative numbers, which is negative.