5 Minute Check on Chapter 2 Transparency 3

5 -Minute Check on Chapter 2 Transparency 3 -1 1. Evaluate 42 - |x - 7| if x = -3 2. Find 4. 1 (-0. 5) Simplify each expression 3. 8(-2 c + 5) + 9 c 4. (36 d – 18) / (-9) 5. A bag of lollipops has 10 red, 15 green, and 15 yellow lollipops. If one is chosen at random, what is the probability that it is not green? 6. Standardized Test Practice: A 8/4 < 4/8 B Which of the following is a true statement -4/8 < -8/4 C -4/8 > -8/4 Click the mouse button or press the Space Bar to display the answers. D -4/8 > 4/8

Lesson 12 -7 Rational Expressions with Unlike Denominators

Click the mouse button or press the Space Bar to display the answers.

Objectives • Add rational expressions with unlike denominators • Subtract rational expressions with unlike denominators

Vocabulary • Least common multiple – • Least common denominator –

Key Concept • Step 1: Find the LCD – use least common multiples of denominator to find LCD • Step 2: Change each rational expression into an equivalent expression with the LCD as the denominator – convert by multiplying top and bottom by another form of 1 • Step 3: Add or subtract just as with rational expressions with like denominators – add or subtract numerators over the denominator • Step 4: Simplify if necessary

Example 1 Find the LCM of Find the prime factors of each coefficient and variable expression. Use each prime factor the greatest number of times it appears in any of the factorizations. Answer:

Example 2 Find the LCM of Express each polynomial in factored form. Use each factor the greatest number of times it appears. Answer:

Example 3 Find Factor each denominator and find the LCD. Since the denominator of needs to be renamed. is already 5 z, only

Example 3 cont Multiply by Distributive Property Add the numerators Answer: Simplify.

Example 4 Find Factor the denominators. The LCD is Add the numerators Answer: Simplify.

Example 5 Find Factor. The LCD is Add the numerators. Multiply. Answer: Simplify

Summary & Homework • Summary: – Rewrite rational expressions with unlike denominators using the least common denominator (LCD). Then add or subtract • Homework: – none