Q1 of 108 Page 36

Find the zeroes of the following quadratic polynomials and verify the relationship between the zeroes and the coefficients.

3x2 – x – 4


To find the zeros of the polynomial let us first solve the polynomial by equating it to zero. Factorizing the given polynomial

3x2 – x - 4 = 0


To factorize the polynomial we have,


Sum of the value should be equal = -1


Product should be equal to = 3 × (-4)


= -12


So two numbers are -4, 3


3x2 – 4x + 3x - 4 = 0


3x (x + 1) -4 (x + 1) = 0


(3x - 4)(x + 1) = 0


3x - 4 = 0 or x + 1 = 0


Now solving first part,


3x-4 = 0


3x = 4


x = 4/3


Now solving the second part,


x + 1 = 0


x = -1


When we compare the above quadratic equation with the generalized one we get,


ax2 + bx + c = 0


a = 3, b = -1, c = -4


Sum of zeroes = -b / a


= - (-1) / 3


= 1/3


Product of zeroes = c / a


= -4 / 3


= -4/3


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