Multiplying and Dividing Fractions

Rule:  To multiply two fractions together we multiply their numerators
together and divide by the product of their denominators.  If the fraction
reduces it helps to reduce before you multiply.


(a/b)(c/d) = (ac)/(bd)
Examples: 
(2/5)(3/7) = 6/35 
[(5x)/(7y)][(14)/(3x)] = [(5x)/(7y)][ [(2)(7)]/[(3x)] ] = [(5)/(y)][(2)/(3)] = 10/(3y) 

Reduce before you multiply.

If numerator or denominator of fractions are polynomials, factor numerator
and denominator, reduce, and then multiply. 
[(2x - 6y)/4][x/(x²  -  9y² )] = [2(x - 3y)/4][x/(x + 3y)(x - 3y)] = [1/2][ [x/(x + 3y)] ] = x/[2(x + 3y)]

Reduce before you multiply.

Rule:  To divide one fraction by another we multiply by the reciprocal
of the divisor or we invert the divisor and multiply.


[a/b]/[c/d] = [a/b][d/c] = [ad]/[bc]
Example: 
[(x²  + 4x - 21)/(3x² )]/[(x²  - 6x + 9)/x] =[ [(x + 7)(x - 3)]/(3x² ) ][ x/[(x - 3)² ] ]

 = (x + 7 )/[3x(x - 3)]  Reduce before you multiply.

Multiplying and Dividing Fractions

Rule: To multiply two fractions together we multiply their numerators together and divide by the product of their denominators. If the fraction reduces it helps to reduce before you multiply.

(a/b)(c/d) = (ac)/(bd)

Rule: To divide one fraction by another we multiply by the reciprocal of the divisor or we invert the divisor and multiply.

[a/b]/[c/d] = [a/b][d/c] = [ad]/[bc]

Example: [(x² + 4x - 21)/(3x² )]/[(x² - 6x + 9)/x] =[ [(x + 7)(x - 3)]/(3x² ) ][ x/[(x - 3)² ] ] = (x + 7 )/[3x(x - 3)] Reduce before you multiply.

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Example:

[(x² + 4x - 21)/(3x² )]/[(x² - 6x + 9)/x] =[ [(x + 7)(x - 3)]/(3x² ) ][ x/[(x - 3)² ] ] = (x + 7 )/[3x(x - 3)] Reduce before you multiply.

Go back to fraction menu.

Go back to home page.

Copyright © 1995 - Present. SSmyrl