(Q25)Verify that 1,-1 and -3 are the zeros of the cubic polynomial x3+3x2-x-3 and check the relationship between zeros and the coefficients.

Answer

Given cubic polynomial

p(x)=x3+3x2-x-3

Comparing the given polynomial with

ax3 + bx2 + cx + d,we get a=1,b=3,c= -1,d= -3

Further given zeros are 1,-1 and -3

p(1)=(1)3 + 3(1)2 - 1 - 3 =

p(-1)=(-1)3 + 3(-1)2 - (-1) - 3 =

p(-3)=(-3)3 + 3(-3)2 - (-3) - 3 =

Therefore 1,-1 and -3 are the zeros of x3+3x2-x-3

So,we take α=1, β=-1 and γ= -3
Now,α+β+γ=1+(-1)+(-3)=-

αβ+βγ+ γα=1(-1)+(-1)(-3)+(-3)1

=-1+3-3=-

=
c
a
=
-
1
= -
αβγ=1(-1)(-3)==
-d
a
=
-()
1
=