Question

The product of two consecutive page numbers is 420. Find the page numbers.

Answer 1

x(x + 1) = 420

we get,

x^2 + x = 420

x^2 + x - 420 = 0

now we can solve this by factoring.

• We have to find two numbers which multiply to make 420, yet have a difference of one.well 21 and 20 fit nicely.

So we get(x + 21)(x - 20) = 420

and x = -21 and x = 20 well,

we can't have negative page numbers,

So,the pages are 20 and 21