Question

Please help, will mark brainliest.

Answer 1

9514 1404 393

Answer:

  a) x = {-1, 3, 4}

  b) (0.472, 13.128)

  c) (3.528, -1.128)

  d) x < 0.472 U x > 3.528

  e) 0.472 < x < 3.528

Step-by-step explanation:

This is a cubic (odd degree) function with a positive leading coefficient, so it will be increasing until the first turning point, and after the last turning point. It will be decreasing between the turning points.

a) A graph shows the zeros to be x = -1, x = 3, x = 4.

b) A graph shows the local maximum to be approximately (0.472, 13.128). The x-coordinate of this point is exactly 2-√(7/3).

c) The local minimum is about (3.528, -1.128). Its x-coordinate is exactly 2+√(7/3).

d) As stated above, the increasing intervals are (-∞, 0.428) ∪ (3.528, ∞).

e) The decreasing interval is (0.428, 3.528).

_____

Additional comments

The sum of odd-degree term coefficients is the same as the sum of coefficients of even-degree terms, so you know one of the roots is -1. Factoring that out gives the quadratic x^2 -7x +12 = (x -3)(x -4), so the other two roots are 3 and 4.

The derivative is 3x^2 -12x +5 = 3(x -2)^2 -7, so its roots (turning points of f(x)) are 2±√(7/3).

I find a graphing calculator can show me the roots and turning points easily.