Question 763738
{{{y=2x^2-9x}}} 
{{{y=2(x^2-(9/2)x)}}} use the formula {{{a^2-2*a*h+h^2=(a-h)^2}}}
{{{y=2(x^2-2*x*(9/4)+(9/4)^2)-(9/4)^2)}}} 
{{{y=2(x^2-9/4)^2-2*(81/16)}}} 
{{{y=2(x^2-9/4)^2-81/8}}}