88.Subtract the sum of and from the sum of and
.
Graph each equation by completing the table of values. See Example 10.
92. 93. 94.
95. 96.
EXERCISES 97–100
FOR INDIVIDUAL OR GROUP WORK
The polynomial equation
gives a good approximation of the age of a dog in human years y, where x represents age
in dog years. Each time we evaluate this polynomial for a value of x, we get one and only
one output value y. For example, if a dog is 4 in dog years, let to find that.
(Verify this.) This means that the dog is about 31 yr old in human years. This illustrates the
concept of a function, one of the most important topics in mathematics.
Exercises 97–100further illustrate the function
concept with polynomials. Work these exercises in
order.
97.It used to be thought that each dog year was
about 7 human years, so that gave the
number of human years for x dog years.
Evaluate yfor and interpret the result.
98.Use the polynomial equation given in the
directions above to find the number of human
years equivalent to 3 dog years.
99.If an object is projected upward under certain conditions, its height in feet is given
by the trinomial
,
where xis in seconds. Evaluate this polynomial for. Use the result to fill in
the blanks: If seconds have elapsed, the height of the object is feet.
100.If it costs $15 to rent a chain saw, plus $2 per day, the binomial gives the
cost to rent the chain saw for xdays. Evaluate this polynomial for. Use the
result to fill in the blanks: If the saw is rented for days, the cost is.
x= 6
2 x+ 15
x=2.5
x=9,
y= 7 x
x= 4 yL31.1
y=-0.0545x^2 +5.047x+11.78
RELATING CONCEPTS
y= 1 x+ 322 y= 1 x- 422
y= 2 x^2 + 2 y=-x^2 + 4 y=-x^2 + 2
y=x^2 - 4 y=x^2 - 6 y= 2 x^2 - 1
t^2 - 10 t+ 3
9 t^3 - 3 t+ 8 t^2 - 8 t+ 4 12 t+ 8
xy
0
1
2
xy
0
1
2
xy
0
1
2
xy
0
1
2
xy
0
1
2
xy
0
1
2
x 23456
y
x
y
328 CHAPTER 5 Exponents and Polynomials
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