Question

Find all zeros of f(x)=x^3−15x−4. Enter the zeros separated by commas

Answer 1

f(x)=x^3−15x−4

p =±4 and q= ±1

p/q =±4

Find one that is a zero using synthetic division.

Let consider 4

 

f(x)=x^3−15x−4

4|  1  0  -15  -4

     0  4   16   4

  ----------------------------

     1  4   1    0

4 is the zero of the function.

The depressed polynomial is x^2+4x+1

Find the roots of x^2+4x+1

Thus zeros are 4,-2-√3 and -2+√3