How do you solve for x in x=18/(x+3)?

2 Answers
Ratnaker Mehta
Jun 23, 2016

x=-6, x=3.

Explanation:

x=18/(x+3)
rArr x(x+3)=18.
rArr x^2+3x-18=0.
rArr x^2+6x-3x-18=0,.........[6xx3=18, 6-3=3.]
rArr x(x+6)-3(x+6)=0.
rArr (x+6)(x-3)=0.
rArr x=-6, x=3.

Clearly, these satisfy the given eqn. hence, the roots are confirmed.

Tony B
Jun 23, 2016

So solutions are x=3" and "x=-6

Explanation:

Multiply both sides by (x+3)

x(x+3)=18xx(x+3)/(x+3)

But (x+3)/(x+3)=1 giving;

x(x+3)=18

Subtract 18 from both sides

x(x+3)-18=18-18

x(x+3)-18=0

Expand the brackets

x^2+3x-18=0 larr" solve as a quadratic"
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Note that (-3)xx6=-18 and that -3+6=+3

=>(x-3)(x+6)=0

So solutions are x=3" and "x=-6

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