PSAT Math : How to evaluate rational expressions

Example Questions

Example Question #2 : Rational Expressions

If √(ab) = 8, and a= b, what is a?

16

4

10

2

64

4

Explanation:

If we plug in a2 for b in the radical expression, we get √(a3) = 8. This can be rewritten as a3/2 = 8. Thus, loga 8 = 3/2. Plugging in the answer choices gives 4 as the correct answer.

9/5

37/15

–37/15

–9/5

–11/5