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solve a/a+5=3/a+1

solving rational expressions

 

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David F. | USNRC Training Professional – Mathematics TutorUSNRC Training Professional – Mathematic...
4.9 4.9 (96 lesson ratings) (96)
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Cross multiply to get:
 
a(a+1) = 3(a+5), expand
 
a2 + a = 3a + 15, set equal to 0
 
a2 - 2a - 15 = 0, factor
 
 
(a - 5) (a + 3) = 0, set each term to 0
 
(a - 5) = 0    and    (a + 3) = 0,  solving for each
 
a = 5   or   a = -3
Jim S. | Physics (and math) are fun, reallyPhysics (and math) are fun, really
4.6 4.6 (151 lesson ratings) (151)
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John, given a/(a+5)=3/(a+1) get rid of the fractions by multiplying both sides by (a+5)(a+1)

which gives a2 - 2a - 15=0 this factors into (a-5)(a+3) so the roots are a=5,-3

Regards

Jim