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algebra

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Find the maximum or minimum of the following quadratic function: y = x2 - x - 56.
A. -56
B. 56
C. -225/4
D. 225/4
d

  • algebra - ,

    1. y=x2 - 16

    for maximum or minumum, dy/dx=0
    hence 2x=0 or x=0

    minimum value of function occurs when x=0 which is y=-16

    2.using same principle as above,
    dy/dx=10x+5

    when dy/dx=0 => 10x+5=0 => x=-1/2

    minimum value of y= -5/4 - 5/2 + 11

    for 3, 4 and 5 use the same principle as 1 and 2

  • algebra - ,

    max: infinity (at x=inf)
    min: x=1/2, y= you figure it. check sign.

  • algebra - ,

    Not sure if you know Calculus, as done by Me

    so let's complete the square

    y = x^2 - x - 56
    = x^2 - x + 1/4 - 1/4 - 56
    = (x- 1/2)^2 - 225/4

    so we have a min of -225/4 , when x = 1/2

    (min because the parabola opens upwards)

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