Evaluate the expression 3x2 + 5xy – 2 for x = 3 and y = -2.
Hint
Plug in 3 for x and -2 for y.
Answer
-5
Example 2
The formula for the surface area of a cone is πrs + πr2, where r is the radius of the base and s is the length of the slant. Find the surface area of a cone with radius 10 cm and a slant of 12 cm (use 3.14 for π).
Hint
Remember that surface area is written in units squared.
Answer
690.8 cm2
Example 3
Evaluate the expression x3 + x2 + x + 1 for x-values equal to -2, -1, 0, 1, and 2.
Hint
Make a chart, yo.
Answer
(-2, -5), (-1, 0), (0, 1), (1, 4), and (2, 15)
Example 4
Which of the following values of x make the equation x2 – 8x = -12 true?