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Unformatted text preview: roberts (eer474) – HW 05 – windle – (56747) 1 This printout should have 8 questions. Multiplechoice 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 xaxis. 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 xaxis when the xintercepts 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 xaxis when c = 3 2 . 002 10.0 points Determine the vertex of the parabola whose xintercepts 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 yintercept 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.
 Fall '08
 Léger
 Math

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