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Do Now 6/7/10. Copy HW in your planner. Text p. 816, #4-36 multiples of 4 In your notebook, find the sum and difference of the fractions below. Objective. SWBAT add and subtract rational expressions. Section 12.6 “Add and Subtract Rational Expressions”.
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Do Now 6/7/10 • Copy HW in your planner. • Text p. 816, #4-36 multiples of 4 • In your notebook, find the sum and difference of the fractions below.
Objective • SWBAT add and subtract rational expressions.
Section 12.6 “Add and Subtract Rational Expressions” • Adding and subtracting rational expressions is similar to adding and subtracting fractions. • Be sure to simplify your answer. Denominator must be COMMON!!!
EXAMPLE 1 Find the sum or difference. Simplify numerator
Least Common Denominator • The LCD of two or more rational expressions is the product of the factors of the denominators of the rational expressions with each common factor used only once. (Common factors) x (Uncommon factors)
EXAMPLE 2 Find the LCM. (Common factors) x (Uncommon factors) (Common factors) x (Uncommon factors)
EXAMPLE 2 Find the LCM. Because c – 2 and 2c +7 cannot be factored, they don’t have any factors in common. The LCM is the product of c – 2 and 2c + 7.
Adding and Subtracting with Different Denominators • To add or subtract rational expressions that have different denominators, use the LCD to write equivalent rational expressions that have the same denominator just as you would for numerical fractions.
EXAMPLE 3 Find the sum or difference. LCD = 24x³
EXAMPLE 4 Find the sum or difference. LCD = 3x(x+2)
EXAMPLE 5 Find the sum or difference. LCD = (x+5)(x – 2)(x + 4)
Try it out…Find the sum or difference. Homework Text p. 816, #4-36 multiples of 4