170 likes | 241 Views
Chapter 11. Quadratic Functions and Equations. The Quadratic Formula. 11.2. Solving Using the Quadratic Formula Approximating Solutions. Solving Using the Quadratic Formula.
E N D
Chapter 11 Quadratic Functions and Equations
The Quadratic Formula 11.2 • Solving Using the Quadratic Formula • Approximating Solutions
Solving Using the Quadratic Formula Each time we solve by completing the square, the procedure is the same. When a procedure is repeated many times, a formula can often be developed to speed up our work. If we begin with a quadratic equation in standard form, ax2 + bx + c = 0, and solve by completing the square we arrive at the quadratic formula.
The Quadratic Formula The solutions of ax2 + bx + c = 0, are given by
Solve 3x2 + 5x = 2 using the quadratic formula. Solution Put it in Standard Form and determine a, b, and c (1 point) Substituting
Substitute a, b, and c into the quadratic formula (1 point).
To Solve a Quadratic Equation • If b = 0, isolate x2 and use the principle of square roots to root both sides. • If b is not 0, try factoring and using the principle of zero products. • If b is not zero and the quadratic is not easily factorable, write the equation in the form x2 + bx + c = 0, if b is even, try completing the square. • 4. If b is not zero, the quadratic is not easily factorable, and b is not even, then use the quadratic formula. • Note: The quadratic formula can always be used and so if time constraints are high, you can always skip 1-3 and try it as a first resort.
Recall that a second-degree polynomial in one variable is said to be quadratic. Similarly, a second-degree polynomial function in one variable is said to be a quadratic function.
Solve x2 + 7 = 2x using the quadratic formula. Solution Put it in Standard Form and determine a, b, and c (1 point)
Substitute a, b, and c into the quadratic formula (1 point).
Solve x2 + 7 = 2x by any method. Solution Check if b is 0. If so, isolate x2 and root both sides. Since b is not 0, check for factoring, a diamond shows it is not factorable. Get standard form and check if b is even for completing the square. Since b is even we complete the square.
Solve x2 + 7 = 2x by any method. 1. Get the form x2 + bx = c (1 point)
Take ½ of b, square it, and add it to both sides. (complete the square) (1 point)
Use the principle of powers to root both sides. Move the constant. State the answer.) (1 point)