Verify that the numbers given alongside of the cubic polynomial are their zeros. Also verify the relationship between the zeroes and the coefficients in each case :
x3 – 4x2 + 5x – 2;2, 1, 1
Let p(x) = x3 – 4x2 + 5x – 2
Then, p(2) = (2)3 – 4(2)2 + 5(2) – 2
= 8 – 16 + 10 – 2
= 0
p(1) = (1)3 – 4(1)2 + 5(1) – 2
= 1 – 4 + 5 – 2
= 0
Hence, 2, 1 and 1 are the zeroes of the given polynomial x3 – 4x2 + 5x – 2.
Now, Let α = 2 , β = 1 and γ = 1
Then, α + β + γ = 2 + 1 + 1 = 4
αβ + βγ + γα = (2)(1) + (1)(1) + (1)(2)
= 2 + 1 + 2
= 5
and αβγ = 2 × 1 × 1
= 2
Thus, the relationship between the zeroes and the coefficients is verified.