# Math 5 - roberts(eer474 – HW 05 – windle –(56747 1...

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Unformatted text preview: roberts (eer474) – HW 05 – windle – (56747) 1 This print-out should have 8 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001 10.0 points Determine the value of c so that the vertex of the graph of the quadratic function f ( x ) = 6 x 2 + 6 x + c lies on the x-axis. 1. c =- 3 4 2. c = 3 3. c =- 3 2 4. c = 3 4 5. c = 3 2 correct Explanation: The graph of f is a parabola, and its vertex will lie on the x-axis when the x-intercepts of the parabola coincide. This occurs when the two solutions of f ( x ) = 6 x 2 + 6 x + c = 0 coincide. By the quadratic formula these so- lutions are x =- 3 ± √ 9- 6 c 3 . Thus the vertex of the parabola lies on the x-axis when c = 3 2 . 002 10.0 points Determine the vertex of the parabola whose x-intercepts are at x = 1 ,- 7 and whose y- intercept is at y = 7. 1. vertex = (- 5 , 16) 2. vertex = (- 3 , 16) correct 3. vertex = (- 2 , 15) 4. vertex = (- 4 , 15) 5. vertex = (- 3 , 17) Explanation: The equation of a parabola having x- intercepts at x = 1 ,- 7 can be written as f ( x ) = A ( x- 1)( x + 7) where A is a constant whose value is deter- mined by the y-intercept of the parabola since f (0) = 7 = ⇒...
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## This note was uploaded on 11/08/2010 for the course M 305G taught by Professor Léger during the Fall '08 term at University of Texas.

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Math 5 - roberts(eer474 – HW 05 – windle –(56747 1...

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