Chapter 4: Quadratic Equations

Example 1. Solve: x² - 4 = 0

Solved:- x² - 4 = 0

(x + 2) (x - 2) = 0

Either x + 2 = 0 which gives x = -2

Or, x - 2 = 0, which gives x = 2

x = -2, 2

Example 2. Solve: 8x² - 22x - 21 = 0

Solution:- 8x² - 22x - 21 = 0

8x² - (28 - 6) x - 21 = 0

8x² - 28x + 6x -21 = 0

4x(2x - 7) + 3(2x - 7) = 0

(2x - 7) (4x + 3) = 0

Either 2x - 7 = 0 or, 4x + 3 = 0

Either 2x = 7 or, 4x = -3

Either x = 7/2 or, x = -3/4