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Unit #3: Quadratics 5-8: The Quadratic Formula. Essential Question: What are some things the discriminate is used for?. 5-8: The Quadratic Formula. Sometimes you’ll run into a quadratic expression that cannot be factored. For example: x 2 + 10x + 4 = 0
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Unit #3: Quadratics5-8: The Quadratic Formula Essential Question: What are some things the discriminate is used for?
5-8: The Quadratic Formula • Sometimes you’ll run into a quadratic expression that cannot be factored. • For example: x2 + 10x + 4 = 0 • There is no combination of numbers that multiplies to get 4 and adds to 10. • Yet, there are real numbers that exist for x to make that a true statement. • There exists a formula that allows you to find the solutions for any quadratic equation, called the QUADRATIC FORMULA
5-8: The Quadratic Formula • A quadratic equation written in standard form ax2 + bx + c = 0can be solved with the quadratic equation
5-8: The Quadratic Formula • The “b2 – 4ac” underneath the square root is called the discriminant. • The discriminant tells us how many (and what type) of solutions we get from the quadratic equation Discriminant
5-8: The Quadratic Equation • The Discriminant • Determine the type and number of solutions of x2 + 6x + 8 = 0 • a = 1, b = 6, c = 8 • Two real solutions
5-8: The Quadratic Equation • Determine the type and number of solutions • x2 + 6x + 9 = 0 • x2 + 6x + 10 = 0 62 – 4(1)(9) = 36 – 36 = 0 1 Real Solution 62 – 4(1)(10) = 36 – 40 = -4 2 Imaginary Solutions
5-8: The Quadratic Formula • What is the quadratic equation?:
5-8: The Quadratic Formula • Empirical verification that the formula works • x2 + 8x + 12 = 0 can be factored as • (x + 6)(x + 2) = 0 meaning • x = -6 OR x = -2 • a = 1, b = 8, c = 12
5-8: The Quadratic Formula • Using the quadratic formula to solve a problem that can’t be factored • x2 + 10x + 4 = 0 • a = 1, b = 10, c = 4
5-8: The Quadratic Formula • Another equation that can’t be factored • 2x2 - 6x + 1 = 0 • a = 2, b = -6, c = 1
5-8: The Quadratic Formula • Use the quadratic equation to solve 2x2 = –6x – 7
5-8: The Quadratic Formula • Assignment • Page 293 • Problems 1 – 21, 31 – 39 (odds) • Show your work • Ignore directions in 23-29 to approximate radical solutions • Leave your answers in simplest radical form