MTH 095 - May 6, 2009
1.
Today we will . . .
- see how to use factoring to solve equations (5.8)
- take the HW Quiz over 7.2, 7.3, 5.4 - 5.6 (both assignments)
2.
Friday we will do Activity #3
3.
Monday we will go over 5.7 and 5.8 HW and review for the
Mod 3 Test
Sec 5.8 is the last one in this mod!
DEADLINE for Mod 3 Test is Friday, May 15.
Jan 4­5:52 PM
ONE MORE EXAMPLE FROM 5.7
Sometimes more than one type of factoring must be used.
Example: Factor the following polynomials.
(a)
8y3 - 50y
(b)
6x2 - 12x + 6
May 5­9:21 AM
1
Sec 5.8: Solving Equations by Factoring and Problem Solving
One reason to factor polynomials is that it allows us to solve certain
kinds of equations.
This technique depends on a special property of zero called the
zero-factor property.
May 1­9:48 AM
Let's use the zero-factor property to solve some equations.
Example: Solve:
(a)
(x - 4)(x + 2) = 0
(b)
(3x + 8)(x -1)(2x + 1) = 0
May 6­9:40 AM
2
If the equation is not already factored, we may have to factor first.
Example: Solve:
(a)
x2 - 2x - 15 = 0
(b)
x2 + 5x + 6 = 0
May 6­9:42 AM
Example: Solve:
(a)
y2 - 10y + 24 = 0
(b)
3y2 - y - 14 = 0
May 6­9:43 AM
3
We may also have to get the equation into the proper form
before factoring.
Example: Solve:
(a)
x2 - 12x = -20
(b)
n(2n - 3) = 2
May 6­9:44 AM
One special application of factoring involves the Pythagorean Theorem,
which describes how the sides of a right triangle are related.
May 6­9:46 AM
4
EXAMPLE: Suppose that the longer leg of a right triangle is 4 feet
longer than the other leg. If the hypotenuse is 20 feet long, find the
lengths of the two legs.
May 6­9:48 AM
5
Attachments
Student Guide to Online Math Help Spring 2009.pdf