The quadratic function f is negative only on the open interval (−2, 1/4 ) and its graph passes through the point (−1, −5). Determine the coefficients of f and sketch its graph.

Respuesta :

Answer:

  f(x) = 4x^2 +7x -2

  graph is attached

Step-by-step explanation:

The zeros of the function are at the ends of the open interval, so are -2 and 1/4. These are values that make the factors of f be zero. This means you can write the function as ...

  f(x) = a(x +2)(4x -1) . . . . for some constant "a"

Then f(-1) = a(-1+2)(4(-1)-1) = a(1)(-5) = -5a. We know f(-1) = -5, so a=1 and the factored equation is ...

  f(x) = (x +2)(4x -1)

Multiplying it out, we have ...

  f(x) = 4x^2 +7x -2

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The axis of symmetry is halfway between the zeros, so is x = -7/8. This is where the minimum will be.

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