Question

Решите уравнение:
27n - 90 = 3n^3 - 10n^2

Answer 1

$27n - 90 = 3n^3 - 10n^2$

$9(3n -10) = n^2(3n - 10)$

$9(3n -10) - n^2(3n - 10)=0\ \ \ |:(-1)$

$-9(3n -10) +n^2(3n - 10)=0$

$(3n -10)(n^2-9)=0$

$(3n -10)(n-3)(n+3)=0$

$n=\frac{10}{3}, n=3, n=-3$