Solved Problem on Division Algorithm for Polynomials
Suppose we have a polynomial P(x) = 0 of degree 3. If we are given a root x = r of that polynomial. We can find the other two roots by dividing the polynomial with (x -r). Let’s see it with an example.
Question 1: Find all the zeros of the polynomial f(x) = 2x3 -5x2 -4x + 3 if one of roots is .
Solution:
x = is a root of the polynomial (Given)
Now we know from the fact stated above, (x – ) is a factor of the given polynomial. So, for finding out the other zeros, we need to divide the polynomial with this factor.
So we get 2x2 -4x – 6 as quotient.
The remaining two roots are roots of this polynomial.
2x2 – 4x – 6 = 0
⇒ 2x2 -6x + 2x – 6 = 0
⇒ 2x(x – 3) + 2 (x – 3) = 0
⇒ (2x + 2) (x – 3) = 0
x = -1 and x = 3
Thus, the remaining two roots are x = -1 and x = 3.
Question 2: Divide the polynomial 5x4 -3x3 + 2x2 – 1 with x3 – 1.
Solution:
The remainder is 3 and quotient is 5x3 + 2x2 + 4x + 4
Question 3: Find all the zeros of 2x4 – 3x3 -3x2 + 6x – 2. We know that two zeros are √2 and -√2.
Solution:
We are given two zeros of the polynomial. We know that, x – √2 and x + √2 are the factors of the polynomial.
Two find the other roots let’s divide the polynomial with both of these.
(x – √2)(x + √2)
= x2 – 2
Dividing the polynomial with x2 – 2.
The quotient polynomial is given by 2x2 – 3x + 1
The remaining two roots are also the roots of this polynomial.
2x2 – 3x + 1
⇒ 2x2 – 2x -x + 1
⇒ 2x(x -1) -1(x – 1)
⇒ (2x – 1) (x – 1) = 0
So, the roots come out to be x = and x= 1.
Thus, all the roots are x = 1, √2, -√2 and
Division Algorithm for Polynomials
Polynomials are those algebraic expressions that contain variables, coefficients, and constants. For Instance, in the polynomial 8x2 + 3z – 7, in this polynomial, 8,3 are the coefficients, x and z are the variables, and 7 is the constant. Just as simple Mathematical operations are applied on numbers, these operations can also be applied on different polynomials, applying different operations on polynomials gives a new polynomial, say p(x) is a polynomial multiplied with q(x), then, the new polynomial g(x) = p(x) × q(x).
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