Question

so tu nhien n thoa man ( n+1)(n+3)=63

 

Answer 1

Có: (n + 1)(n + 3) = 63

=> n² + 4n + 3 - 63 = 0

=> n² + 4n - 60 = 0

=> n² - 6n + 10n - 60 = 0

=> n(n - 6) + 10(n - 6) = 0

=> (n - 6)(n + 10) = 0

=> n - 6 = 0 => n = 6

hoặc n + 10 = 0 => n = -10

Vậy n = 6 , n = -10