All of the equations contain -4 in their range. A) -4 = sqrt(x) - 5 1 = sqrt(x) x = 1; valid B) -4 = sqrt(x) + 5 -9 = sqrt(x) x = 81; valid C) -4 = sqrt(x + 5) 16 = x + 5 x = 11; valid D) -4 = sqrt(x - 5) 16 = x - 5 x = 21 I believe the equations contain square instead of square root, in which case the answer would be A because no other could have a negative range.