[tex]\bf 14)\\\\
(x-3y)^2\implies \stackrel{5}{x^2}-6\stackrel{11}{xy}+\stackrel{7}{y^2}\implies 5-66+7\\\\
-------------------------------\\\\
15)\\\\
(x+n)(x+1)=x^2+x+nx+n\implies x^2+(x+nx)+n
\\\\\\
\stackrel{x^2}{x^2}~+~\stackrel{m}{(1+n)}\stackrel{x}{x}~+~\stackrel{5}{n}\qquad
\begin{cases}
n=5\\
m=1+n\\
\qquad 6
\end{cases}[/tex]
