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Unformatted text preview: Lescure, Etienne – Review 1 – Due: Dec 10 2007, 10:00 pm – Inst: Diane Radin 1 This printout should have 20 questions. Multiplechoice questions may continue on the next column or page – find all choices before answering. The due time is Central time. 001 (part 1 of 1) 10 points Find the derivative of g when g ( x ) = x 4 cos x . 1. g ( x ) = x 4 (3 cos x sin x ) 2. g ( x ) = x 3 (4 cos x x sin x ) correct 3. g ( x ) = x 3 (4 sin x x cos x ) 4. g ( x ) = x 3 (4 cos x + x sin x ) 5. g ( x ) = x 4 (3 sin x cos x ) 6. g ( x ) = x 3 (4 sin x + x cos x ) Explanation: By the Product rule, g ( x ) = x 4 ( sin x ) + (cos x ) · 4 x 3 . Consequently, g ( x ) = x 3 (4 cos x x sin x ) . keywords: derivative, product rule, trigono metric function 002 (part 1 of 1) 10 points Find the derivative of the function f ( x ) = 3 2 x x . 1. f ( x ) = 6 2 x x 2 2. f ( x ) = 6 2 x x 3 3. f ( x ) = 4 3 x x 3 correct 4. f ( x ) = 4 3 x x 2 5. f ( x ) = 4 + 3 x x 3 Explanation: After simplification, 3 2 x x = 3 x 2 x 2 . Thus by the Quotient Rule, f ( x ) = 3 x 2 2 x (3 x 2) x 4 . Consequently, f ( x ) = 4 3 x x 3 . keywords: derivatives, quotient rule 003 (part 1 of 1) 10 points Find the derivative of f when f ( x ) = sin x 1 4 cos x . 1. f ( x ) = cos x 4 (1 4 cos x ) 2 correct 2. f ( x ) = sin x 4 1 4 cos x 3. f ( x ) = cos x + 4 1 4 cos x 4. f ( x ) = cos x + 4 (1 4 cos x ) 2 5. f ( x ) = sin x 4 cos 2 x (1 4 cos x ) 2 Lescure, Etienne – Review 1 – Due: Dec 10 2007, 10:00 pm – Inst: Diane Radin 2 6. f ( x ) = cos x 4 sin 2 x (1 4 cos x ) 2 Explanation: By the Quotient Rule, f ( x ) = cos x (1 4 cos x ) 4 sin x sin x (1 4 cos x ) 2 = cos x 4 (cos 2 x + sin 2 x ) (1 4 cos x ) 2 . But cos 2 x + sin 2 x = 1, so f ( x ) = cos x 4 (1 4 cos x ) 2 . keywords: derivative, trigonometric function, quotient rule 004 (part 1 of 1) 10 points There is one point in the first quadrant at which the tangent line to the graph of y = 5 + x + x 2 x 3 is horizontal. Find the ycoordinate of this point. 1. y = 6 correct 2. y = 8 3. y = 7 4. y = 9 5. y = 5 Explanation: The tangent line to the graph will be hori zontal when dy dx = 1 + 2 x 3 x 2 = (3 x + 1)(1 x ) = 0 . The only solution of this for which x > 0 oc curs at x = 1. But at x = 1 the corresponding value of y is y = 6. Since this value of y is positive, the only point in the first quadrant at which the tangent line is horizontal is the point P = (1 , 6) . keywords: horizontal tangent line, derivative, extrema, polynomial 005 (part 1 of 1) 10 points If f is a function defined on ( 2 , 2) whose graph is 1 2 1 2 1 2 1 2 which of the following is the graph of its derivative f ? 1. 1 2 1 2 1 2 1 2 Lescure, Etienne – Review 1 – Due: Dec 10 2007, 10:00 pm – Inst: Diane Radin 3 2....
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This note was uploaded on 03/18/2008 for the course M 408k taught by Professor Schultz during the Spring '08 term at University of Texas.
 Spring '08
 schultz

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