f(x)= x[tex]x^2+x-30[/tex
= [tex](x)^2+2*x*\frac{1}{2} +(\frac{1}{2} )^2-(\frac{1}{2} )^2-30[/tex]
= [tex](x+\frac{1}{2} )^2-\frac{1}{4} -30[/tex]
= [tex](x+\frac{1}{2} )^2-\frac{121}{4}[/tex]
=[tex](x+\frac{1}{2} )^2-30\frac{1}{4}[/tex] (Answer)
