Practice questions
- In this equation, what is the value of x – y?
A. 2 B. 3 C. 4 D. 5
- What is the value of a in the equation if b2 = 5 and a < 0?
A. –1 B. –2 C. –3 D. –4
Answers and explanations
- The correct answer is Choice (C).
Start with the fraction and subtract the exponents, just as you'd do to divide any other terms with like bases:
You know that 16 equals 24, so set 24 equal to the 2 with the subtracted exponents: 2x–y = 24 Therefore x – y = 4.
- The correct answer is Choice (C).
Simplify the exponential expression by multiplying the exponents, just as you'd do for any other base with an exponent of an exponent:
You know that 16 equals 24, so set 24 equal to the 2 with the subtracted exponents:Therefore, a2 – b2 = 4. You know that b2 = 5, so plug in the value of b2:You also know that a < 0, so a has to be –3.