Example 1: Solve x2 – 11x – 12 = 0
Example 2: Solve 20x2 + 7x – 3 = 0
Example 3: Solve -2n2 – 10n + 12 = 0
Example 4: solve 16x2 – 56x + 49 = 0
Example 6: Solve (x – 1)(x + 9) = 11
Example 7: A room contains 78 chairs. The number of chairs per row is one more than twice the number of rows. Find the number of rows and the number of chairs per row.
Example 8: A strip of uniform width cut from both sides and both ends of an 8-inch by 11-inch sheet of paper reduces the size of the paper to an area of 40 square inches. Find the width of the strip.
Example 9: One length of a right triangle is 2 centimeters more than twice as long as the other leg. The hypotenuse is 1 centimeter longer than the longer of the two legs. Find the length of the three sides of the right triangle.