Multiply n by 3 than square the result

Lets say n was 7. 7 * 3 = 21, 21 * 21 = 441.

N multiplied by 3 is 3n, then to square the result put the entire term in parentheses and raise it to the second power: (3n)^2 , which can be further simplified to 3^2 x n^2 = 9n^2