Linear And Quadratic Functions Worksheet With Answers Page 6

CHAPTER 4. LINEAR AND QUADRATIC FUNCTIONS

4.3 #62. Find the minimum value of the quadratic function f (x) = 4x

8x + 3.

Solution: (b)

The minimum value occurs at the vertex, which has x-coordinate

= 1.

2·4

Then f (1) =

1 is the minimum height.

4.3 E. A store selling calculators has found that, when the calculators are sold at a price

of p dollars per unit, the revenue R (in dollars) as a function of the price p is R(p) =

750p

+ 15000p. What is the largest possible revenue? That is, ﬁnd the maximum value

of the revenue function.

Solution: (d)

The graph is a parabola, opening down, so to ﬁnd the maximum value we

15000

need to ﬁnd the y-coordinate of the vertex. We get x =

= 10.

2·( 750)

1500

The maximum revenue is R(10) =

750(10)

+ 15000(10) =

75000 + 150000 = 75000.

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