Answer :
Given the following expression:
[tex](x-7)^2[/tex]You need to remember that, by definition:
[tex]\begin{gathered} (a+b)^2=a^2+2ab+b^2 \\ (a-b)^2=a^2-2ab+b^2 \end{gathered}[/tex]In this case, you can identify that:
[tex]\begin{gathered} a=x \\ b=7 \end{gathered}[/tex]Then, substituting values and evaluating, you get the following:
[tex]\begin{gathered} (x-7)^2=x^2-2(x)(7)+(7)^2=x^2-14x+49 \\ \\ \end{gathered}[/tex]The answer is:
[tex]x^2-14x+49[/tex]