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Clearing an Equation of Fractions and Decimals

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					Clearing an Equation of Fractions and Decimals
Section 3-6

How to clear an equation of fractions
• To clear an equation of fractions, multiply EVERYTHING by the LEAST COMMON MULTIPLE. This will get rid of the fractions and make solving the equation so much easier . • What LEAST COMMON MULTIPLE would I use to get rid of the fractions in this equation? 1/3p + 1/6 = 3/2 • The LEAST COMMON MULTIPLE you should use is 6.

More on clearing an equation of fractions…
• Now multiply EVERYTHING by 6. (6) (1/3p + 1/6) = (6) (3/2) • You now have: (6) x (1/3p) + (6) x (1/6) = (6) (3/2) • After multiplying, you should get: 2p + 1 = 9 2p = 9 – 1 2p = 8
(“p” wants to be by itself, so divide everything by 2)

2p/2 = 8/2 p = 4.

More on clearing an equation of fractions…
• Please solve this equation: 3/4a – 7 = 8 + 2/3a • Multiply everything by its LCD, 12? (12) (3/4a – 7) = (12) (8 + 2/3a) • Now you have: 9a – 84 = 96 + 8a • 9a – 8a = 96 + 84 1a = 180 or a = 180

How to clear an equation of decimals
• To clear an equation of decimals, multiply EVERYTHING by the smallest possible power of 10. This will make your job easier when solving an equation because you will deal with normal #’s rather than decimals. • What would you use to multiply if you have: • 10.4 + 3.2y = 4
(multiply by 10)

• 100.43 – 7y + 4.2 = 3.2
(multiply by 100)

More on clearing an equation of decimals…
• What power of 10 would you use to get rid of all the decimals in this equation? 0.5r + 1.5 = 3.0 • You should use 10 to multiply EVERYTHING . • Now you have: (10) (0.5r + 1.5) = (10) (3.0) • Now you get: (10) (0.5r) + (10) (1.5) = (10) (3.0) 5r + 15 = 30 5r = 30 – 15 5r = 15 5r/5 = 15/5 1r = 3 or r = 3

More on clearing an equation of decimals…
• Please solve this equation: 0.21c + 4.52 = -0.73 – 0.84c • Choose the smallest power of 10, which is 100, to multiply EVERYTHING. (100) (0.21c + 4.52) = (100) (-0.73 – 0.84c) 21c + 452 = -73 – 84c 21c + 84c = -73 – 452 105c = -525 105c/105 = -525/105 1c = -5 or c = -5


				
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posted:11/25/2009
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