a positive number is 20 less than its square. what is the number?

Question

a positive number is 20 less than its square. what is the number?

Answer 1

Let the number be x.

So x=x²-20

x²-x-20 =0

(x-5)(x+4)=0

x=5 or x=-4

since the number is positive, it is 5.