If two zeroes of the polynomial p(x) = 2x4 + 7x3 - 19x2- 14x + 30 are √2 and - √2 then find the other two zeroes.
Given: p(x) = 2x4 + 7x3 - 19x2- 14x + 30
Since x = √2 & - √2 is a solution so
x- √2 & x + √2 are two factors of p(x)
Multiplying the two factors we get x2-2 …Equation 1
which is also a factor of p(x)
To get the other two factors we need to perform long division
On performing long division we will get
2x2 + 7x -15 …Equation 2
Equation 2 is also a factor of p(x)
To find the other two zeroes of the polynomial we need to solve Equation 2
We use the method of factorization for solving Equation 2
2x2 + 7x -15 = 0
⇒ 2x2 + 10x -3x -15 = 0
⇒ 2x(x + 5) -3(x + 5) = 0
⇒ (2x-3)(x + 5) = 0
The two roots are and -5