# Basic Algebra

### Example 1

Evaluate the expression 3x^{2} + 5xy – 2 for x = 3 and y = -2.

### Example 2

The formula for the surface area of a cone is *πrs + πr ^{2}*, 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).

### Example 3

Evaluate the expression x^{3} + x^{2} + x + 1 for x values equal to -2, -1, 0, 1, 2.

### Example 4

Which of these values of x (1, 2, 3, 4, 5, 6) make this equation true:

x^{2} – 8x = -12?