Answer:
x - 1
Explanation:
To get one factor of the cubic expression x³+3x²+x-5 according to the remainder theorem we can say that
x³+3x²+x-5 = 0
Then we apply Ruffini's Rule and obtain
x³+3x²+x-5 = (x-1)(x²+4x+5)
where x = 1 is the only real root of the polynomial expression.