5.5 Quadratic Equations

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Zero-Product Property

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If ab = 0, then a = 0 or b = 0.

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Example:

x² - 4x - 21 = 0

Smoke jumpers are in free fall from the time they jump out of a plane until they open their parachutes. The function y = -16t² + 1600 models a jumper's height y in feet at t seconds for a jump from 1600ft. How long is a jumper in free fall if the parachute opens at 1000ft.?

Solving by Graphing

When the graph of the function intersects the x-axis, the value of the function is zero, and each x-value is a zero of the function.

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A zero of a function is a solution of the equation ax² + bx + c = 0.

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Solve by graphing

x² - 5x + 2 = 0

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