We have, 5x2 – 8x – 4
= 5x2 – 10x + 2x – 4
= 5x (x–2) + 2 (x – 2)
= (5x + 2) (x – 2)
So, the value of 5x2 – 8x – 4 is zero when 5x + 2 = 0 or x – 2 = 0
i.e., when x = –2/5 or x = 2
Therefore, the zeroes of 5x2 – 8x – 4 are –2/5 and 2.
Sum of zeroes =
=
Product of zeroes =
=
Verify that 3, -1, are the zeroes of the cubic polynomial p(x) = 3x3 – 5x2 –11x – 3 then verify the relationship between the zeroes and the coefficients.
Kind a cubic polynomial with the sum, sum of the product of its zeroes taken two at a time and the product of its zeroes as –9, –11, 30 respectively.