45.In Example 6 ,we determined that the quadratic function defined by
modeled the number of higher-order multiple births, where xrepresents the number of
years since 1995.
(a)Use this model to approximate the number of higher-order births in 2006 to the near-
est whole number.
(b)The actual number of higher-order births in 2006 was 6540. (Source:National Center
for Health Statistics.) How does the approximation using the model compare to the
actual number for 2006?
46.Should the model from Exercise 45be used to approximate the rate of higher-order mul-
tiple births in years after 2006? Explain.
y=-69.15x^2 +863.6x+ 4973
540 CHAPTER 9 Quadratic Equations, Inequalities, and Functions
EXERCISES 47– 48
Recall from Section 3.3that the x-value of the x-intercept of the graph of the line
is the solution of the linear equation. In the same way, the
x-values of the x-intercepts of the graph of the parabola are the real
solutions of the quadratic equation.
In Exercises 47– 48, the calculator graphs show the x-values of the x-intercepts of
the graph of the polynomial in the equation. Use the graphs to solve each equation.
47.
48.x^2 + 9 x+ 14 = 0
x^2 - x- 20 = 0
ax^2 +bx+c= 0
y=ax^2 +bx+c
y=mx+b mx+b= 0
TECHNOLOGY INSIGHTS
5
–25
–10 10
5
–25
–10 10
10
–10
–10 10
10
–10
–10 10
Complete each factoring. See Section 6.1.
Solve each quadratic equation by factoring or by completing the square. See Section 9.1.
- 53.x^2 + 6 x- 3 = 0 54.x^2 + 8 x- 4 = 0
x^2 + 3 x- 4 = 0 x^2 - x- 6 = 0
- 2 x^2 + 6 x= 1 x^2 - 3 x 2 - 3 x^2 - 15 x= 1 x^2 + 5 x 2
PREVIEW EXERCISES
