Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and equations ensures a solution.
If a and b are constants, what is one solution of the equation (x + a)(x - b) = 0?
(1) a = 4
(2) b = 3
==> In the original condition, x=-a, and thus we have 2 variables -a,b, meaning we need 2 equations to match the number of variables. Since we have 1 each for both (1), (2) the answer is likely C. Using both (1) & (2) together, x=-4,3 is our solution yet it is not unique, and thus NOT sufficient. Therefore the best answer is E
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