1. Practice 1 Practice 2 Practice 3 Warm Up Use a calculator to evaluate. Round the results to the nearest hundredth.

2. 9-4A Solving Quadratic Equations by Using the Quadratic Formula You will need a calculator for today’s lesson. Algebra 1 Glencoe McGraw-HillLinda Stamper

3. Today you will solve quadratic equations by using the quadratic formula: The quadratic formula is read as “x equals negative b, plus or minus the square root of b squared minus 4ac, all divided by 2a.” The quadratic formula gives the solutions of ax 2 + bx + c = 0 in terms of the coefficients a, b, and c.

4. x equals negative b, plus or minus square root, b squared minus 4ac, all over 2a.” Sing-a-long: Pop Goes the Weasel Sing – a – long competition by rows.

5. Write the equation in standard form. Identify values of a, b, and c. Write problem. Rewrite in standard form. Identify values for a, b, and c. The first step in using the quadratic formula is to identify the values of a, b, and c.

6. Example 1 Write the equation in standard form. Identify the values of a, b, and c. Example 2 Write the equation in standard form. Identify the values of a, b, and c.

7. Solve the equation. Identify values for a, b, c. Write quadratic formula.

8. Solve. If the solution involves radicals, round to the nearest tenth. Identify values for a, b, c. Write quadratic formula. Rewrite the equation in standard form.

9. Example 3 Example 4 Example 5 Solve. If the solution involves radicals, round to the nearest tenth. Round in the last step!

10. Example 3 Solve. If the solution involves radicals, round to the nearest tenth.

11. Solve. If the solution involves radicals, round to the nearest tenth. Example 4 Example 5

12. 9-A12 Page 497-499 #9-20,29–31,60-62.

13. 2 Keystrokes for TI-30X IIS Use a calculator to evaluate. Round the results to the nearest hundredth. When evaluating radical expressions that are not perfect squares, round the answer in the last step. ( + 2 nd √ 3 ) ) ÷ 4 1 ( - 2 √ 3 ) ) ÷ 4 1 = = Does your calculator have order of operations?

14. Keystrokes for TI-30X A Use a calculator to evaluate. Round the results to the nearest hundredth. When evaluating radical expressions that are not perfect squares, round the answer in the last step. 1 2 X 3 √ = ÷ 4 + 1 2 X 3 √ = ÷ 4 - = =

15. When using the quadratic formula, it is helpful to change the value under the radical to addition when simplifying. Find the value of b 2 – 4ac for the equation. Write problem. Identify the values for a, b and c. Write the expression. Simplify. (Place values in parentheses and change subtraction to addition to avoid sign errors.)

16. Example 3 Find the value of b 2 – 4ac for the equation.