Warm Up Use a calculator to evaluate Round

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

9 -4 A Solving Quadratic Equations by Using the Quadratic Formula You will need a calculator for today’s lesson. Algebra 1 Glencoe Mc. Graw-Hill Linda Stamper

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 4 ac, all divided by 2 a. ” The quadratic formula gives the solutions of ax 2 + bx + c = 0 in terms of the coefficients a, b, and c.

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

The first step in using the quadratic formula is to identify the values of a, b, and c. 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.

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.

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

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

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

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

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

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

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

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 – 4 ac 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. )

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