Find the solution set of 2√x = x - 3.
A. {1, 9}
B. {9}
C. {1, -9}
I got a quadratic and factored it as (x - 9)(x - 1). Then the solutions are x = 9 and x = 1. But the answer is supposed to be just 9.
However, wouldn't x = 1 also work, if we do √1 = -1?
yes, but √1 is not -1!
The use of √ implies the positive value. √25=5, not ±5.
Just because (-5)^2 is also 25 does not mean that you can say √25 = -5.