Question 997671

{{{2y^2 -6y -56}}}

{{{2(y^2 -3y) -56}}}

{{{2(y^2 -3y+_)-2*_ -56}}}....recall {{{(a-b)^2=a^2-2ab+b^2}}};you have {{{a=1}}} and {{{2ab=3}}}, find {{{b}}}

{{{2ab=3}}}=>{{{2*1*b=3}}}=>{{{2b=3}}}=>{{{b=3/2}}}

square it and plug it in {{{2(y^2 -3y+_)-2*_ -56}}}

{{{2(y^2 -3y+(3/2)^2)-2*(3/2)^2 -56}}}

{{{2(y -3/2)^2-cross(2)*(9/cross(4)2) -56}}}

{{{2(y -3/2)^2-9/2 -56}}}

{{{2(y -3/2)^2-9/2 -112/2}}}

{{{2(y -3/2)^2-121/2}}}