1. Giant Pandas Giant pandas eat about 30 pounds of bamboo every day. About how many pounds of bamboo will a giant panda eat in 2 days? in 3 days? in 4 days? In the Real World The function rule below relates the pounds of bamboo a panda eats to the number of days. Pounds of Bamboo = 30  Number of days Functions 12 5. A function is a pairing of each number in one set with a number in a second set. Starting with a number in the first set, called an input, the function pairs it with exactly one number in the second set, called an output.

2. Evaluating a Function EXAMPLE 1 To solve the problem about about giant pandas, you can make an input-output table. Use the function rule p = 30d, where d is the number of days (input) and p is the pounds of bamboo eaten (output). ANSWER A giant panda will eat about 60 pounds of bamboo in 2 days, about 90 pounds in 3 days, and about 120 pounds in 4 days. Input Days, d Substitute in the function p = 30d Output Pounds eaten, p 1 2 3 4 p = 30(4) p = 30(3) p = 30(2) p = 30(1) 30 60 90 120 Functions 12 5.

3. Write a function rule for the input-output table. Using a Table to Write a Rule EXAMPLE 2 Input, x Output, y Input, m Output, n SOLUTION Each output y is 4 less than the input x. A function rule is y = x – 4. m3m3 Each output n is the input m divided by 3. A function rule is n =. 10 11 12 13 6 7 8 9 3 39 6 0 1 2 0 Functions 12 5. SOLUTION

4. Making a Table to Write a Rule EXAMPLE 3 PatternMake an input-output table using the number of squares s as the input and the number of triangles t as the output. Then write a function that relates s and t. SOLUTION ANSWER Each output value is 2 times the input value.There are 2 triangles for every square. A function rule for this pattern is t = 2 s. Squares, s Triangles, t 1234 63 84 4 1 2 2 Functions 12 5.