Jawsh,

A rational number is almost the same thing as a fraction. The only differences are that some people don't consider "fraction" to include negative fractions such as -3/5 (this distinction is made more in junior high school than elsewhere), and a rational number is independent of how it's represented so that 1/2, 3/6, and 0.5 are all the same rational number. (Technically the first two are equivalent fractions but not the same fraction; and the third is not a fraction but a terminating decimal, representing the decimal fraction 5/10. However, we may use the equals sign between them even if we call them fractions. Every rational number has a "main" fraction representing it, namely the fraction in lowest terms.)

If a is positive (or 0) √(a²) = a
If a is negative, √(a²) = |a| = -a (which is bigger than 0)

So 3 √(49) = 3 √(7²) = 3 × 7 = 21

Good Hunting!
RD