Advanced Math/fractions

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Expert: Sherry Wallin - 11/4/2010


Question

math equation
attached is a scanned copy of my math equation. thank you

Answer
Lisa~

I can barely see your scan!

To multiply two mixed numbers without making them into improper fractions you must use a rule that is called the distributive rule:

a(b+c) = a*c + b*c, and a simple example would be:
3(2+4) = 3*2+3*4 = 6+12 = 18

also note a mixed number is the sum of the whole part and the fraction part, so 1(1/2) is 1 + (1/2). So suppose I want

2(1+(1/2)) = 2*1 + 2(1/2) = 2 + 1 = 3

another example is suppose I want to multiply

(2+3)(1+2) = 2(1+2) + 3(1+2) = 2(1) + 2(2) + 3(1) + 3(2)
= 2 + 4 + 3 + 6 = 15 so to do your problem:

2(1/3) * 3(4/5)
= [2 + (1/3)]*[3 + (4/5)]
= 2[3 + (4/5)] + (1/3)[3 + (4/5)]
= 2(3) + 2(4/5) + (1/3)3 + (1/3)(4/5)
= 6 + (8/5) + 1 + (4/15)
= 6 + 1 + (8/5) + (4/15)
= 7 + (3/3)(8/5) + (4/15)
= 7 + (24/15) + (4/15)
= 7 + (24+4)/15
= 7 + 28/15 but 28/15 is 1 + 13/15
= 7 + 1 + 13/15
= 8 + 13/15
= 8(13/15)

which is the same as converting each mixed number to an improper fraction and multiplying:
2(1/3) * 3(4/5) = (7/3)(19/5) = (7(19))/(3(5)) = 133/15 = 8(13/15)

Math Prof  
    Questioner's Rating
    Rating(1-10)Knowledgeability = 10Clarity of Response = 10Politeness = 10
    Commentthank you very much for your input on this equation. this helps me to understand how to set up future equations.


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Sherry Wallin

Expertise

I can answer most questions up through Calculus and some in Number Theory and Abstract Algebra.

Experience

I have had my Bachelor's Degree since 1987 and have been a teacher since 1988. I earned my Masters Degree in Mathematics May 2010. I have been teaching at the same community college since 2002.

Education/Credentials
I have taught 12 years at the community college level, medical college, and technical college as well as a high school instructor and alternative education instructor and charter school instructor.

Awards and Honors
Master's GPA 3.56 Bachelor's GPA 3.34 Post grad work not degree related GPA 4.0

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