Q1 of 227 Page 82

Find the zeros of the following quadratic polynomials and verify the basic relationships between the zeros and the coefficients.

6x2 – 3 – 7x

Let f(x) = 6x2 – 3 – 7x

Arranging equation in proper form.


Now, f(x) = 6x2 – 7x – 3


To find out zeros of the given polynomial.


We put f(x) = 0


6x2 – 7x – 3 = 0


To find out roots of this polynomial we use splitting of middle term method.


According to this method we need to find two numbers whose sum is – 7 and product is – 18.


6x2 – (9 – 2)x – 3 = 0


6x2 – 9x + 2x – 3 = 0


3x(2x – 3) + 1(2x – 3) = 0


(3x + 1)(2x – 3) = 0


3x + 1 = 0


x = .


Again, 2x – 3 = 0


x =


Our zeros are α = and β = .


sum of zeros = α + β = +


sum of zeros = α + β =


Product of zeros = αβ = .


Now, Comparing f(x) = 6x2 – 7x – 3 with standard equation ax2 + bx + c.


We get, a = 6, b = – 7 and c = – 3.


We can verify,


Sum of zeros =


i.e. α + β =


α + β =


Product of zeros =


αβ =


Hence, relationship between zeros and coefficient is verified.


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