解高次方程?

x^5 + x^6 = -243x - 243
==> x^6 + x^5 + 243x + 243 = 0
==> x^5(x + 1) + 243(x + 1) = 0
==> (x + 1)(x^5 + 243) = 0
==> x + 1 = 0 或 x^5 + 243 = 0
==> x = -1 或 x^5 = -243 = (-3)^5
所以,
x = -1 或 -3 (實數解)
(ps. 若包括虛數, 它有 6 個解.)

x^5+x^6=-243x-243
x^5(x+1)=-243(x+1)
x^5=-243
x=-3

x^5+x^6=-243x-243
x^5(x+1)= -243(x+1)
x^5 =-243
x=-3