Foreach of the following functions use the quadratic formula to findthe zeros of f. Then, find the maximum or minimum value of f(x). (a)f(x)=x^2 -8x (b)f(x)=-2x^2-9x+5

kadejoset

kadejoset

Answered question

2022-07-28

Foreach of the following functions use the quadratic formula to find the zeros of f. Then, find the maximum or minimum value of f(x).
(a) f ( x ) = x 2 8 x
(b) f ( x ) = 2 x 2 9 x + 5

Answer & Explanation

Selden1f

Selden1f

Beginner2022-07-29Added 14 answers

a. f ( x ) = x 2 8 x
x 2 8 x = 0
x(x-8) = 0
so, the zeros are at 0 and 8.
min val = 0
max val = 8
Since a > 0, it has a minimum. The minimum value of f(x) is-16 when x is 4. The maximum and minimum of the parabola is thevertex.So, this is determined by finding the vertex x = -b/2a, thensubstituting x to find the value of f(x)
b) f ( x ) = 2 x 2 9 x + 5
( 2 x 2 + 9 x 5 ) = 0
(2x - 1) (x + 5) = 0
So the zeros are at x = 1/2 and x=-5
Since a< 0, then it will have a maximum. Using the vertexformula again, we find the max is 121/8 when x is -9/4.

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