Question

what is the perimeter of the square? 4x + 12 (b) what is the area of the square?

Explanation:

Step1: Recall area formula for square

The area formula of a square is $A = s^2$, where $s$ is the side - length of the square. Here, the side - length $s=x + 3$.

Step2: Expand the expression

We expand $(x + 3)^2$ using the formula $(a + b)^2=a^2+2ab + b^2$. Here $a=x$ and $b = 3$. So, $(x + 3)^2=x^2+2\times x\times3+3^2=x^2+6x + 9$.

Answer:

$x^2+6x + 9$