Question

Как решить все вот эти примеры?
(k-p)(p+k)
(u+5)(5-u)
(4s-1)(4s+1)
(6+5y)(5y-6)
(7g+9h)(9h-7g)

Answer 1

(k - p)(p + k) = (k - p)(k + p) = k² - p²
(u + 5)(5 - u) = (5 + u)(5 - u) = 25 - u²
(4s - 1)(4s + 1) = (4s)² - 1 = 16s² - 1
(6 + 5y)(5y - 6) = (5y + 6)(5y - 6) = (5y)² - 36 = 25y² - 36
(7g + 9h)(9h - 7g) = (9h + 7g)(9h - 7g) = (9h)² - (7g)² =
                             = 81h²-49g²