Math111i_Quiz9_Solutions

# Math111i_Quiz9_Solutions - 1 8 above the vertex Thus we see...

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Math 111I Sec 001 Quiz 9 Solutions Name Directions: Read each question carefully and answer in the space pro- vided. The use of calculators is allowed, but not necessary. There are 10 points possible. To receive partial credit on any problem work must be shown. 1. For the following plot, give the ( x,y ) coordinates for the vertex. Solutions. The vertex of the parabola is the maximum point attained, and that point is (2 , 5). 2. Find f ( - 1) for the function f ( x ) = 4 x 2 + 8 x - 7 . Solutions. We see that f ( - 1) = 4( - 1) 2 + 8( - 1) - 7 = 4 - 8 - 7 = - 11

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Math 111I Sec 001 Quiz 9 Solutions 3. Find a for the quadratic polynomial f ( x ) = ax 2 with the focus at (0 , 0 . 125). Solutions. We know that the vertex of the function f ( x ) = ax 2 is located at (0 , 0). Further we know that the focus is located ± ± 1 4 a ± ± = 0 . 125 =
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Unformatted text preview: 1 8 above the vertex. Thus we see that 4 a = 8, and a = 2. So we have that our function is f ( x ) = 2 x 2 . 4. Upon retirement, you begin to receive money from a retirement ac-count. The function M ( t ) = 970 , 000 e-. 14 t , gives the amount of money remaining in the account, M ( t ), after t years of retirement. How many years of retirement before the account balance reaches \$78,000? Solutions. We want to know how many years passed for M ( t ) = 78000. So we solve the following equation 78000 = 970000 e-. 14 t 78000 970000 = e-. 14 t ln ² 78 970 ³ = ln ( e-. 14 t ) ln ² 78 970 ³ =-. 14 t ln ( 78 970 )-. 14 = t So we see that t ≈ 18 . 00...
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Math111i_Quiz9_Solutions - 1 8 above the vertex Thus we see...

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