A trinomial square has two possible forms:
[tex]\begin{gathered} (a+b)^2=a^2+2ab+b^2 \\ (a-b)^2=a^2-2ab+b^2 \end{gathered}[/tex]So, for us to check if
[tex]x^2-8x+64[/tex]Is a trinomial square, we first check if the first and thrid terms are positive, because both options has positive first and thrid terms, even if a or b are negative, because they are squared in the process.
Both are positive, x² and 64.
Now, by comparison, we see that, in thi case we would have:
[tex]\begin{gathered} a=x \\ b^2=64 \\ b=8 \end{gathered}[/tex]If it is a trinomial square, than the middle term has to be:
[tex]-2ab[/tex]We use the negative form because we have a negative middle term.
So, let's see if it checks out:
[tex]-2ab=-2x\cdot8=-16x[/tex]We got -16x, but the middle term is -8x, they don't match.
Since they don't match, the given expression is not a trinomial square. The answer is No.
