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Rational Numbers & Equations. Lesson 3-5. Rational Numbers & Equations. When given an equation with a fraction… Solve by multiplying by the reciprocal Solve by canceling fractions using the LCD (lowest common denominator). Solving by a fraction.
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Rational Numbers & Equations Lesson 3-5
Rational Numbers & Equations When given an equation with a fraction… • Solve by multiplying by the reciprocal • Solve by canceling fractions using the LCD (lowest common denominator)
Solving by a fraction To “solve” with a fraction multiply by the reciprocal given Multiply by reciprocal [Check for cross reducing] (Fractions cancelled out) Solve! 2 m = 200 3 3 . 2 m= 200 . 3 2 3 2 m = 100 • 3 m = 300
Solving by a fraction 2 y = 8 5 5 . 2 y = 8 . 5 2 5 2 y = 4 • 5 y = 20 - b = 2 8 -8 • - b = 2 • -8 8 b = 2 • -8 b = -16
Solving a fraction equation To “solve” with fractions in the problem multiply all terms by the LCD given Multiply all equation terms by LCD [Cross reduce to cancel denominators] New equation Solve! 1 x + 3 x = 5 2 4 (4) 1 x + (4) 3 x = 5 (4) 2 4 2x + 3x = 20 5x = 20 x = 4
Solving a fraction equation y + y = -4 8 12 (24) 2y+ (24) 3y= -4 (24) 8 12 6y + 6y = -96 12y = -96 y = -8
Practice… Solve… • _ 3 f = 6 4 • -2 = 4c 9 • 2y + y = 22 3 4 • 3n – 2 = -7 5
Homework p. 131 #14-17, 19-22, 31-33