Question

find all the zeroes of the polynomial x³+3x²-5x-15, if two of its zeroes are √5 and -√5​

Answer 1

Step-by-step explanation:

Let the three zeroes are alpha, beta & gama .

We know that

for this Cubic polynomial x³ + 3x² - 5x - 15

alpha + beta + gama = -b/a

√5 + (-√5) + gama = -3/1 = -3

√5 - √5 + gama = -3

gama = -3

Third zero is -3 .

So , all the zeroes are √5 , -√5 & -3 .