Question 340226: The product of page numbers on two facing pages of a book is 420. Find the page numbers.
x(x + 1) = 420 is as far as I am.... Help!!! Found 2 solutions by fractalier, Alan3354:Answer by fractalier(6550) (Show Source):
You can put this solution on YOUR website! Okay, you're good so far...so from
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, sooooo...
the pages are 20 and 21
