2. L9-5 Obj: Students will add and subtract rational expressions

3. L9-5 Obj: Students will add and subtract rational expressions

5. Adding and Subtracting Rational Expressions
LESSON 9-5
Additional Examples
An object is 24 cm from a camera lens. The object is in focus on the film when the lens is 12 cm from the film. Find the focal length of the lens.

6. Find the least common multiple of 2x2 – 8x + 8 and 15x2 – 60.
Adding and Subtracting Rational Expressions
LESSON 9-5
Additional Examples
Find the least common multiple of 2x2 – 8x + 8 and 15x2 – 60.
Step 1:  Find the prime factors of each expression.
2x2 – 8x + 8 = (2)(x2 – 4x + 4) = (2)(x – 2)(x – 2)
15x2 – 60 = (15)(x2 – 4) = (3)(5)(x – 2)(x + 2)
Step 2: Write each prime factor the greatest number of times it appears
in either expression. Simplify where possible.
(2)(3)(5)(x – 2)(x – 2)(x + 2) = 30(x – 2)2(x + 2)
The least common multiple is 30(x + 2)(x – 2)2.

8. 1
3x2 + 21x +30 4x
3x + 15
Simplify + .

9. Adding and Subtracting Rational Expressions
x2 – 2x – 3 3
4x + 4
Simplify – .

12. Adding and Subtracting Rational Expressions1 x 1 y +
Simplify . 2 y 1 x –

14. Homework L9-5 (p 525) #10-20e 28-48e skip 42

15. Review of graphing
1. Graph

16. 2.

17. 3.
HW: L9-5 (p 525) #10-20e 28-48e skip 42