Question 807912


{{{sqrt(3x+4) + x  = 12}}}......move {{{x}}} to the right


{{{sqrt(3x+4)  = 12-x}}}...square both sides



{{{(sqrt(3x+4))^2  = (12-x)^2}}}

{{{3x+4  = 12^2-24x+x^2}}}

{{{0= 144-24x-3x-4+x^2}}}

{{{x^2-27x+140=0}}}.......factor completely, write {{{-27x}}} as {{{-20x-7x}}} 

{{{x^2-20x-7x+140=0}}}....group

{{{(x^2-20x)-(7x-140)=0}}}

{{{x(x-20)-7(x-20)=0}}}

{{{(x-7)(x-20)=0}}}

solutions:

if {{{(x-7)=0}}}=> {{{x=7}}}

if {{{(x-20)=0}}}=> {{{x=20}}}