Warm Up Find the product. 1. 5 • 5 • 5 • 5 625 2. 3 • 3 • 3 27 3. (–7) • (–7) • (–7)‏ –343 4. 9 • 9 81

If a number is in exponential form, the exponent represents how many times the base is to be used as a factor. A number produced by raising a base to an exponent is called a power. Both 27 and 33 represent the same power. Exponent Base 7 2

Example 1: Writing Exponents Write in exponential form. A. 4 • 4 • 4 • 4 B. (–6) • (–6) • (–6)‏ 44 (–6)3 C. 5 • 5 • d • d • d • d 52d4 Read –(63) as “ negative 6 to the 3rd power” or “negative 6 cubed”. Reading Math

Write in exponential form. Check It Out: Example 1 Write in exponential form. A. x • x • x • x • x B. d • d • d x5 d3 C. 7 • 7 • b • b 72b2

Example 2: Simplifying Powers = 3 • 3 • 3 • 3 • 3 = 243 B. (–3)5 = (–3) • (–3) • (–3) • (–3) • (–3)‏ = –243 Helpful Hint Always use parentheses to raise a negative number to a power.

Example 2: Simplifying Powers C. (–4)4 = (–4) • (–4) • (–4) • (–4)‏ = 256 D.  

Example 3: Order of Operations Evaluate x(yx – zy) + x for x = 4, y = 2, and z = 3. y x(yx – zy) + xy 4(24 – 32) + 42 4(16 – 9) + 16 4(7) + 16 28 + 16 44

Evaluate z – 7(2x – xy) for x = 5, y = 2, and z = 60. Check It Out: Example 3 Evaluate z – 7(2x – xy) for x = 5, y = 2, and z = 60. z – 7(2x – xy) 60 – 7(25 – 52)‏ 60 – 7(32 – 25) 60 – 7(7) 60 – 49 11

Write in exponential form. 1. n• n • n• n n Lesson Quiz Write in exponential form. 1. n• n • n• n 4 n 2. (–8) • (–8) • (–8) • (h) (–8)3h 3. Evaluate (–4)4 256 4. Evaluate x • z – yx for x = 5, y = 3, and z = 6. –213 5. A population of bacteria doubles in size every minute. The number of bacteria after 5 minutes is 15  25. How many are there after 5 minutes? 480