In my Calculus I assigment, I'm stuck on the following :
Find $M_1=(x_1,y_1)$ on $y=5x+6$ and $M_2=(x_2,y_2)$ on $y=-(x-3)^2+4$ such that the square of the distance between $M_1$ and $M_2$ is minimal.
I'm fine with that, but they add the following : formulate the problem using a fourth degree polynomial implying only variables $x_1$ and $x_2$.
I did :
Be $D=(x_1-x_2)^2+((5x_1+6)-(-(x_2-3)^2+4))$ the distance we want to minimize, then $D=x_1^2+2x_2^2-2x_1x_2+5x_1-6x_2+11$ when expanded.
I don't understand where that "fourth degree polynomial" will appear?