[tex]n-a\ number\\\\(n+9)^2=n^2+2(n)(9)+9^2=n^2+18n+81\\\\Used\ (a+b)^2=a^2+2ab+b^2[/tex]
Answer:
(x+9)²
Step-by-step explanation:
The square of the sum of a number and 9 is in terms of x, is (x+9)²
