y=(x-3)^2-4x^2-x+4
"1-take derivative of the function with respect to x"
(d y)/(d x)=2(x-3)*1-8x-1
"1-equalize with zero and solve for x"
2(x-3)-8x-1=0
2x-6-8x-1=0
-6x-7=0
-6x=7
x=-6/7
"write x=-6/7 in the original equation and calculate for y"
y=(-6/7-3)^2-4(-6/7)^2-(-6/7)+4
y=(-27/7)^2-4(36/49)+6/7+4
y=729/49-144/49+34/7
y=585/49+34/7
y=585/49+238/49
y=823/49
y=16.8