Answer: (1,5)
f(x)=4*x^2+-8x+9
f(x)=4*(x^2+-2x+9/4 ( Factor out )
f(x)=4*(x^2+-2x+(-1)^2+-1*(-1)^2+9/4) ( Complete the square )
f(x)=4*((x+-1)^2+-1*(-1)^2+9/4) ( Use the binomial formula )
f(x)=4*((x+-1)^2+1*5/4) ( simplify )
f(x)=4*(x+-1)^2+5 ( expand )