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Comparing Fractions 2

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    Use < , > , = to compare the two fractions 21/28
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    and 6/9. So there is a buch of ways to do this.
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    The easiest way is if they have the same
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    denominator, we can compare the numerators.
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    Unfortunately we do not have the same denominators
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    So we could do is we could find common denominators
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    for both the fractions and convert both the fractions
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    to have common denominators and compare the
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    numerators.Or even more simply we can
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    simplify them first and then try do it.
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    So 21/28 , they are both divisibley by 7.
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    Let us divide the numerator & denominator by 7
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    21 divide by 7 & 28 divide by 7.
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    Since we are dividing both by 7, we are not changing
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    the value of the fraction 21 ÷ 7 = 3
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    28 ÷ 7 = 4.
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    So 21/28 = 3/4.
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    Lets us do the same thing for 6/9
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    6 & 9 are both divisible by 3
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    So lets divide both 6 & 9 by 3
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    6 ÷ 3 = 2
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    9 ÷ 3 = 3
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    21/28 = 3/4
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    6/9 = 2/3
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    So we really can compare 3/4 & 2/3.
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    The real benefit of doing this, it is easy to find
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    common denominators for this than 28 &9
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    which means we need to multiply larger numbers
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    here we have smaller numbers.
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    the common denominator of 3/4 & 2/3 is the LCM
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    of 4 & 3.
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    4 & 3 does not share any prime factors with each other
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    so LCM of 4 & 3 is the product of the 2 numbers
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    3/4 = /12
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    2/3 = /12
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    I got 12 by multiplying 3 & 4 as they have no
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    common factors. another way to think is
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    prime factorization of 4 = 2x2
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    3 is already a prime number, so prime factorization
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    of 3 is 3.
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    The number that has all prime factors of 4 & 3 is 2,2 & 3
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    2x2x3 = 12.This is how we get LCM
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    to get from 4 to 12 ,you got to multiply 3
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    We multiply denominator by 3 to get 12
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    We need to multiply the numerator by 3
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    3 x 3 = 9
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    To get from 3 to 12, we multiply denominator by 4
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    We also have to multiply numerator by 4
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    4 x 2 = 8
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    21/28 = 3/4 = 9/12
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    6/9 = 2/3 = 8/12
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    Which of these is a greater fraction.
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    Since we have common denominator, we need to
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    look at the numerator. We know 9 > 8
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    So, 21/28 > 6/9
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    And we are done.
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    Another way to do is
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    we need not simply it. just do it for fun.
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    If we did not simplify it 21/28 & 6/9
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    LCM of 28 & 9
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    prime factorization of 28 = 2x2x7
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    Prime factorization of 9 = 3x3
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    The LCM of 28 & 9 must contain 2x2x3x3x7
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    which is esentially 28x9 = 252
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    The common denominator is going to be 252
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    To go from 28 to 252 we had to
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    multiply 28 by 9 ; 28 x 9
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    So we also have to multiply numerator by 9
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    21x9 = 189
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    To go from 9 to 252
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    we need to multiply by 28.
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    So we need to multiply numerator by 28
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    So 6x28 = 168
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    Now we have a common denominator here
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    and we can compare the numerator.
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    189 > 168
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    So 21/28 > 6/9
Title:
Comparing Fractions 2
Description:

u2_l1_t5_we2 Comparing Fractions

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Video Language:
English
Duration:
07:08
Vetrivel Foundation edited английски език subtitles for Comparing Fractions 2
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