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imc

prealgebra junior

Problem

What is the value of if ?
(A)
(B)
(C)
(D)
Solution
is the distance between and ; is the distance between and . Therefore, the given equation says is equidistant from and , so . Alternatively, we can solve by casework (a method which should work for any similar problem involving absolute values of real numbers). If , then and , so we must solve , which has no solutions. Similarly, if , then and , so we must solve , which also has no solutions. Finally, if , then and , so we must solve , which has the unique solution .
Final answer
D