✓
G
P
for Example 3
UIDED
RACTICE
WHAT IF?
In Example 3, find the year when 4750 films were produced.
4.
For Your Notebook
CONCEPT SUMMARY
Methods for Solving Quadratic Equations
Method
Lesson(s)
When to Use
Factoring
9.4–9.8
Use when a quadratic equation can be
factored easily.
Graphing
10.3
Use when approximate solutions are
adequate.
Finding square roots
10.4
Use when solving an equation that can
2
5 d.
be written in the form x
Completing the square
10.5
Can be used for any quadratic equation
2
1 bx 1 c 5 0 but is simplest to apply
ax
when a 5 1 and b is an even number.
Quadratic formula
10.6
Can be used for any quadratic equation.
E
4
Choose a solution method
X A M P L E
Tell what method you would use to solve the quadratic equation. Explain
your choice(s).
2
2 7 5 0
2
1 4x 5 0
2
1 9x 2 4 5 0
a.
10x
b.
x
c.
5x
Solution
a.
The quadratic equation can be solved using square roots because
2
5 d.
the equation can be written in the form x
The equation can be solved by factoring because the expression
b.
2
1 4x can be factored easily. Also, the equation can be solved by
x
completing the square because the equation is of the form
2
1 bx 1 c 5 0 where a 5 1 and b is an even number.
ax
The quadratic equation cannot be factored easily, and completing
c.
the square will result in many fractions. So, the equation can be
solved using the quadratic formula.
✓
G
P
for Example 4
UIDED
RACTICE
Tell what method you would use to solve the quadratic equation. Explain
your choice(s).
2
1 x 2 6 5 0
2
2 9 5 0
2
1 6x 5 5
x
x
x
5.
6.
7.
673
10.6 Solve Quadratic Equations by the Quadratic Formula