Friday

July 25, 2014

July 25, 2014

Posted by **Andrea** on Tuesday, October 31, 2006 at 8:07pm.

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

**Related Questions**

Algebra- Maximum and minimum. - I dont understand how to find the maximum and ...

math - Determine whether the given quadratic function has a minimum value or ...

math - Determine whether this function has a mzximum or minimum value and then ...

Maximum and Minimum - Its been awhile since I have done compleating the square, ...

algebra - given the following quadratic equation, determine if it has a maximum ...

Math - How to find coordinates of vertex, and find out if the function has ...

math - find the vertex, the line of symmetry and the maximum or minimum value of...

Math/Algebra...can you check this please... - f(x)= -4(x+5)^2+3 The vertex is...

Calculus - Find the absolute maximum value and the absolute minimum value, if ...

maths - #1 x + 2y < 18 x + y < 10 2x + y < 18 x, y > 0 Maximize z = ...