### Home > CALC > Chapter 7 > Lesson 7.1.3 > Problem7-30

7-30.

Greta is trying to solve $x − 3\sqrt { x }= −2$ . She decides to simplify the problem by letting $u =\sqrt { x }$.

1. Rewrite Greta's equation using $u$, then solve for $u$.

$\text{If }u=\sqrt{x},\text{ then }u^{2}=x .$

$u^2 − 3u = −2$
Solve for $u$.

If $u = 2$ and $u = 1$, what is $x$?

2. Suppose $x = 5$, what would $u$ be?

Refer to the given information.