The product of two consecutive room numbers is 420. find the room numbers.

Hello:

the consecutive room numbers are : n, n+1

n (n+1) = 420

n²+n - 420 = 0

the discriminant delta = b² - 4ac (a = 1 and b = 1 and c = - 420

delta = (1) ²-4 (1) (-420) = 1681 = 41²

n = (-1 - 41) / 2 (refused negatif number)

or

n = (-1+41) / 2 = 20

the room numbers. are : 20, 21