The difference of a number and 10 is equal to three times the positive square root of the number. Find the number.
A)29
B)27
C)26
D)25
E)28

Question

Quizplus · Accepted Answer

The equation based on the given statement is $x - 10 = 3\sqrt{x}$. Squaring both sides to eliminate the square root gives $(x - 10)^2 = 9x$. Expanding and simplifying, $x^2 - 20x + 100 = 9x$, which simplifies to $x^2 - 29x + 100 = 0$. Factoring or using the quadratic formula, we find that $x = 25$ is the positive solution that satisfies the original equation.

The Difference of a Number and 10 Is Equal to Three