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Comp2.1cc.ppt
- 1. 2.1 Operations with Fractions
- 2. Fraction Review Numerator: Top number in a fraction Denominator: Bottom number in a fraction 4 5
- 3. Adding and Subtracting Fractions Adding and Subtracting Fractions 1) Must have like denominators (Find the LCD- lowest common denominator) 2)Rewrite the fraction with the LCD 3) Add or subtract numerators, denominators stays the same 4) Write in simplified/ proper form
- 4. Adding and Subtracting Unlike Fractions 5 + 1 12 3 1st Find common denominators (what will both numbers go into) 5 + 4 12 12 2nd Add the numerators together 5 + 4 12 9 12 Don’t forget to SIMPLIFY (REDUCE) 3 4
- 5. Adding and Subtracting Unlike Fractions 1/12 + 3/16 = 13/48 5/6 + (- 2/3) = 1/6 - 4/15 - 7/25 = - 41/75
- 6. Finding the Perimeter 3 1 3 2 3 3 •Perimeter: Distance around the figure Add terms with like denominators + = 1 = 5 4 5 2 5 6 5 1 + = = 1 2 5 3 1 3 2 5 4 P= 1 +1 1/5 = 2 1/5
- 7. Finding the Perimeter (same problem just worked different) 3 1 3 2 •Perimeter: Distance around the figure 2 5 5 4 2 + 2 + 4 + 1 5 3 5 3 6 + 10 + 12 + 5 = 15 15 15 15 (3) (5) (3) (5) Don’t forget what you multiply the bottom by you have to multiply the top by the same # (3) (3) (5) (5) 33 15 or 2 1/5
- 8. Using Fractions Ms. Cunningham is making brownies for her Pre-Algebra class. The recipe calls for 2 ¾ cups of flour. She can only find ½ cup in cupboard. How much must she borrow?
- 9. Using Fractions 2 ¾ - ½ Find common denominators 2 ¾ - 4 2 2 ¼ cups =
- 10. Simplify… the fraction! 3x – 4x + 3x 6 8 2 1) Find the LCD that 2, 6, 8 all go into 24 (3) (4) (12) (12) (4) (3) 12x - 12x + 36x 24 24 24 2) Write the Equivalent Fraction 0x + 36x = 36x 24 24 24 3) Add or Subtract Fractions Don’t Forget to Simplify (Reduce your Answer to simplest form) 36x = 3x 24 2
- 11. Simplify… the fraction! 4y – y + 3y 5 4 8 1) Find the LCD that 5, 4, 8 all go into 40 (10) (8) (5) (5) (8) (10) 32y - 10y + 15y 40 40 40 2) Write the Equivalent Fraction 22y + 15y = 37y 40 40 40 3) Add or Subtract Fractions Don’t Forget to Simplify (Reduce your Answer to simplest form) 37y 40
- 12. Review Multiplying/Dividing Fractions Mixed Fraction: whole # with fraction Improper Fraction: numerator is larger than denominator
- 13. Review Multiplying/Dividing Fractions cb ad Multiplying/Dividing Fractions: Fractions must be in improper form. Multiplication Division Multiply straight across -Change ÷ to (multiplication) -Change 2nd # to its reciprocal (flip the fraction over) -Multiply Straight Across c a d b cd ab = c a d b c a b d = =
- 14. Formulas Area: square units inside shape Area of a square A =(length) · (width) Area of a triangle A = ½(base) · (height)
- 15. Find the Area 3 2 5 1 5 1 1 ft 2 ft A = ½(base)·(height) A = ½(2 ft) · (1 ft) Change to improper fraction 3 2 A = ½( ft) · ( ft) 11 5 5 3 Multiply across A = ½( ft) = 55 15 55 30 Simplify A =55 ÷ 5 = 30 ÷ 5 or 1 ft 5 6 11 6 ft²
- 16. Find the Area A =(length) · (width) 2 1/4ft 4 3/4 ft A = (2 ¼ ft) · (4 ¾ ft) Change to improper fraction A = (9/4 ft) · (19/4 ft) A = (171/16 ft) Multiply across Simplify A = (171 ft) 16 = 10 11 ft 16
- 17. Dividing Fractions 4 3 ÷ 2 3 4 5 Multiply the bottom number by the whole number and then add the top number to it to get your new top number 4 x 4 + 3 = 19 5 x 2 +3= 13 19 ÷ 13 4 5 19 • 5 4 13 95 52 = 143 52