Answer:
x+4 square meters
Step-by-step explanation:
In general, when we have two expressions [tex](x+a)[/tex] and [tex](x+b)[/tex]:
[tex](x+a)(x+b)=x^2+(a+b)x+ab[/tex]
In words, the coefficent of the middle term is the sum of a and b, and the last term is the product of a and b. In our given expression:
[tex]a+b=13\\ab=36[/tex]
Thankfully, we're already given one of these terms: [tex]a=9[/tex]. Solving for b in that first equation, we get
[tex]9+b=13\\b=4[/tex]
9 × 4 is 36, so this result checks out! So, with a length of [tex](x+9)[/tex] meters, our width must be [tex](x+4)[/tex] meters.
