I am going to go with the assumption that your equation is [tex]x^2+mx+n=0[/tex]. If there is only one solution, then the equation must be a perfect square. So square [tex](x+3)[/tex] to solve for the equation in the similar form that is given. [tex](x+3)^2=x^2+6x+9=0[/tex]. So the variables match up perfectly in the equation, meaning that the value of m is 6, letter choice C.
