math

posted by .

I'm having some troubles with these. Thanks in advance.

If a>0 find the minimum value. If a<0 find the maximum value.

1. y=-x²+2x+5
2. y=-2x²-3x+4

These are functions for parabolas, so
f(x)=ax²+bx+c when a does not equal 0

In both your examples, the "a", which is the coefficient of the x^2 term, is negative.

1. dy/dx = -2x + 2, and that equals zero at a maximum or minimum. So the maximum would occur at x=1.
d2y/dx^2 = -2. Since that is always negative, x=1 is a point of maximum value.

Do #2 similarly.

Thank-you, but I really don't understand what you mean by dy/dx. I'm feeling terribly stupid, but nothing like that is in my book.

Find Minimum or maximum value of f(x)=2x^2 + 3x -9

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. Algebra- Maximum and minimum.

    I don't understand how to find the maximum and minimum. Determine whether the given quadratic function has a minimum value or maximum value. Then find the coordinates of the minimum or maximum point. 15.f(x) = -x2 + 2x - 4 20.f(x) …
  2. Maximum and Minimum

    Its been awhile since I have done compleating the square, can you please help me?
  3. Algebra2

    Complete parts a – c for each quadratic function. a. Find the y-intercept, the equation of the axis of symmetry and the x-coordinate of the vertex. b. Make a table of values that includes the vertex. c. Use this information to graph …
  4. math

    find a such that f(x)= ax2-4x+3 has a maximum value of 12
  5. math

    find a such that f(x)= ax2-4x+3 has a maximum value of 12
  6. math

    Determine whether the given quadratic function has a minimum value or maximum value. Then find the coordinates of the minimum or maximum point.f(x) = x2 + 2x - 9
  7. Math

    1.What is the smallest possible value of 2x^4+(8/x^4) over all real nonzero values of x?
  8. math

    Maximum or minimum values of the function f(x) = (1 – x)^2 e^x is: i need solution (a) Minimum value at x = –1; maximum value x = 1 (b) Minimum value at x = 1; maximum value x = –2 (c) Minimum value at x = 1; maximum value x …
  9. calculus

    Find the absolute extrema of the function (if any exist) on each interval. (If an answer does not exist, enter DNE.) f(x) = square root of (25 − x^2) (a) [−5, 5] minimum (x, y) = (smaller x-value) (x, y) = (larger x-value) …
  10. MATHS

    The quadratic function f(x) has roots at x=4 and x=-2 and has value of 2 at x=0. Does f(x) have a minimum or maximum?

More Similar Questions