If |x^2 − 20| = x, which of the following could be the value of x?
Choose the correct choice from the following options
A) -5 B) -4 C) 1 D) 4 E) 10
The LHS is not negative, so the RHS is also not negative. Thus x &gt;= 0.   First, let's assume that x^2-20 is negative.   -(x^2 - 20) = x   x^2 + x - 20 = 0   (x+5)(x-4) = 0   x = 4 or x = -5 (However, x can not be negative.)   Then x = 4 is a possible value for x.   The answer is 4.
<result>D</result>
If |x^2 − 20| = x, which of the following could be the value of x?