Ch 2 Fractions Flashcards
List the Num and Den Rules for positive fractions?
Numerator inc, fraction **inc **ex- multiplying the numerator of a positive proper fraction by 3/2 will inc the fraction - (3/2 is greater than 1 called improper fraction).
Denominator inc, fraction dec b/c now you have more pieces of a pie so your portion dec.
Adding the same # to the numerator & denominator will bring the fraction closer to 1 so if the original fraction is smaller than 1, fraction will inc as it approaches 1
Will the given operation inc, dec, stay the same?
1) Multiply a positive, proper fraction by 3/8? Dec bc 3/8 (.375) is less than 1 so multiplying by a number that is less than 1, will dec the fraction.
2) Multiply both the num and den of a positive, proper fraction by 7/2? Stay the same bc we are multiplying by the same number which is essentially 1.
3) Divide a positive, proper fraction by 3/13? Inc = Dividing a positive # by a positive, proper fraction inc the #.
Which fraction is greater 7/9 or 4/5?
When comparing fractions, never divide fraction to work with decimals. Always use fractions to save time.
Method 1) Compare fractions by finding common den: 7/9=35/45 4/5=36/45. Therefore 4/5 > than 7/9
Method 2) Shortcut - Cross multiply the fraction and put each ans by the corresponding num. 7/9 or 4/5? (7*5)=35 or (4*9)=36. Therefore 4/5 > 7/9.
Simplify: 10x/(5+x)
Rule: when simplifying fractions that include sums or diff, you may split up the terms of the num but never split the den
Ans: Cannot to simplifed bc you cannot split the denominator.
Simplify the following complex fractions:
1) (15+10)/5= 15/5+10/5= 3+2=5
2) 5/(15+10)= 5/25= 1/5: DO Not Split the den
3) (15+10)/(5+2)= 25/7
4) (5x-2y)/(x-y)= Cannot to simplified bc den cannot be simplified.
5) (6x-15y)/10= 6x/10-15y/10= 3x/5-3y/2
Simplify: 12ab3-6a2b/3ab
Since there is sub in the num, first factor out common term in num and than cancel as necessary:
Ans: 6ab(2b2-a)/3ab=2(2b2-a)
