when the square of a certain number is diminished by 9 times the number the result is 36. Find the number

Question

 I need help please. 

Answer 1

n = the number

 

n² - 9n = 36

 

n² - 9n - 36 = 0

 

(n - 12)(n + 3) = 0

 

n = 12 or -3