Question 1076346

{{{25x^2+30-12=0}}}....I assume you forgot to put {{{x}}} after {{{30}}}

{{{(25x^2+30x)-12=0}}}

{{{25(x^2+(30/25)x)-12=0}}}

{{{25(x^2+(6/5)x)-12=0}}}.....recall the rule:{{{(a+b)^2=a^2+2ab+b^2}}}...in your case we need {{{b^2}}} part to complete square

{{{25(x^2+(6/5)x+b^2)-25*b^2-12=0}}}...we already have {{{a=1}}} and {{{2ab=6/5}}} and we can calculate {{{b}}}

{{{2*1*b=6/5}}}

{{{b=(6/5)/2}}}

{{{b=(cross(6)3/5)/cross(2)1}}}

{{{b=3/5}}}


{{{25(x^2+(6/5)x+(3/5)^2)-25*(3/5)^2-12=0}}}

{{{25(x^2+(6/5)x+9/25)-cross(25)*(9/cross(25))-12=0}}}

{{{25(x+3/5)^2-9-12=0}}}

{{{25(x+3/5)^2-21=0}}}