Cross multiply to get:

a(a+1) = 3(a+5), expand

a

^{2}+ a = 3a + 15, set equal to 0a

^{2}- 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

John S.

asked • 04/18/13solving rational expressions

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Cross multiply to get:

a(a+1) = 3(a+5), expand

a^{2} + a = 3a + 15, set equal to 0

a^{2} - 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

John, given a/(a+5)=3/(a+1) get rid of the fractions by multiplying both sides by (a+5)(a+1)

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

Regards

Jim

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