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Lesson 6-2. Proportions. Obj : 1) To solve proportions 2) To use proportions to solve problems. HWK: p 300 2-40 even Vocab : 1) proportion 2) cross products – products obtained after cross multiplying 2 ratios in a proportion. Key Concepts: Cross Products.
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Lesson 6-2 Proportions
Obj: 1) To solve proportions2) To use proportions to solve problems • HWK: p 300 2-40 even • Vocab: 1) proportion • 2) cross products – products obtained after cross multiplying 2 ratios in a proportion
Key Concepts: Cross Products • In a proportion, the cross products are equal • Arithmetic Algebra • 6 = 8a = c • 9 12 b d • 6 · 12 = 9 · 8 ad = bc where b≠0 and • d ≠0
Tell whether the two ratios form a proportion. Explain • Ex 1) 3 , 21 Ex 2) 15 , 5 • 5 35 20 7
Solve each proportion • Ex 3) 2 = y Ex 4) 22 = 6 • 7 14 d 21
Ex 5) 7 = x • 12 30
Ex 6) 100 rods is about 275 fathoms. About how many fathoms is 25 rods?