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9.5 Adding and Subtracting Rational Expressions. 4/23/2014. Same Denominator:. When adding or subtracting fractions with same denominators, add/subtract the numerators and keep the same denominator. Example 1. 3. 5. +. 2 x. 2 x. 3. 5. 8. 3. 5. +. Add numerators and simplify. . =.
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Same Denominator: When adding or subtracting fractions with same denominators, add/subtract the numerators and keep the same denominator
Example 1 3 5 + 2x 2x 3 5 8 3 5 + Add numerators and simplify. = = + 2x 2x 2x 2x Add and Subtract with Like Denominators Perform the indicated operation.
Different Denominators: If the denominators are different, find the least common denominator (LCD).
Example 2 1 1 a. 6x 8x3 Find the LCD of Rational Expressions Find the least common denominator. , List the multiples of the number: 6: 6, 12, 18, 24, 30, 36…. 8: 8, 16, 24, 32… Take the Least Common Multiple (LCM): 24 As for the variable, take the one with highest exponent: LCD:
Example 2 1 1 , b. 2x 4 3x 9 – + Find the LCD of Rational Expressions Find the least common denominator. 2x - 4 = 2(x – 2) 3x + 9 = 3(x + 3) 2: 2, 4, 6, 8… 3: 3, 6, 9, 12… LCD: 6(x-2)(x+3) (Take the LCM and multiply by the rest of their factors)
Example 2 3 x , c. x 2 x2 4 – – Find the LCD of Rational Expressions Find the least common denominator. Factors LCD:
Example 2 x x1 – , d. 2x 1 x1 + + Find the LCD of Rational Expressions Find the least common denominator. Factors LCD:
4: 4, 8, 12, 16.. 3: 3, 6, 9, 12… LCD: 12 Basic Example of Adding Fractions with different denominators. 9 4 13
Perform the indicated operation. 3 4 a. + 2x x2 Example 3 Add with Unlike Denominators Find LCD:
Example 3 Add with Unlike Denominators Find LCD:
Perform the indicated operation. ANSWER 2 3 3x 4 + 7. + x2 2x 2x2 Add and Subtract with Unlike Denominators Checkpoint
ANSWER x2 2x 3 3 x + + 8. + x1 x1 – + x 1 x 1 ( ) ( ) – + Add and Subtract with Unlike Denominators Checkpoint Perform the indicated operation.
Example 4 Add with Unlike Denominators Add: Find LCD:
Homework: 9.5 p.497 #10, 12, 13, 15, 16-24even, 28, 30, 33, 37, 39
Example 1 x 2 – x x 3 3 + + x 2 – x 2 – Subtract numerators. = x 3 x 3 + + x 3 + Subtract with Like Denominators Subtract.
Example 2 – – x x 2 2 x 2 – Subtract with Like Denominators Perform the indicated operation. = = =
Subtracting Polynomials Switch the signs of everything that’s being subtracted and combine like terms. Ex:
Example 3 – x 3 2x – x 4 x 4 + + Subtract with Like Denominators Perform the indicated operation. = = =
Example 4 Subtract with Unlike Denominators LCD: Subtract = = = =
Example 5 1 2 – x2 x 2 x2 4 – – – Subtract with Unlike Denominators Subtract = -2 LCD: -2 1 = -1 = =
ANSWER x 2 1 1 – – – x2 1 x 1 x 1 ( ) ( ) – – + x 1 + Add and Subtract with Unlike Denominators Checkpoint Perform the indicated operation.
Homework: 9.5 p.497 # 11, 14, 17-23odd, 29, 31, 32, 38,40, 41