Given:
[tex](x+9)^2[/tex]
To find:
The given expression as a trinomial in standard form.
Solution:
We have,
[tex](x+9)^2[/tex]
Using the formula, [tex](a+b)^2=a^2+2ab+b^2[/tex], we get
[tex](x+9)^2=x^2+2(x)(9)+(9)^2[/tex]
[tex](x+9)^2=x^2+18x+81[/tex]
Standard form a trinomial is [tex]ax^2+bx+c[/tex].
[tex]x^2+18x+81[/tex] is in the standard form.
Therefore, the required expression is [tex]x^2+18x+81[/tex].