From a perfect square trinomial
[tex]a^2+2ab+b^2[/tex]We know that:
[tex]2ab=2\cdot\sqrt[]{a^2}\cdot\sqrt[]{b^2}[/tex]Now, let's use this for the trinomial given:
[tex]x^2-8x+b^2[/tex]We know that:
[tex]-8x=2\cdot x\cdot b^2[/tex]Solving for b,
[tex]\begin{gathered} -8x=2xb \\ \rightarrow b=-\frac{8x}{2x}\Rightarrow b=-4 \end{gathered}[/tex]This way, the complete perfect square trinomial is:
[tex]x^2-8x-16[/tex]Ans: Option A
