If $α$ and $β$ are the zeros of the quadratic polynomial $f(x)\ =\ ax^2\ +\ bx\ +\ c$, then evaluate:
$α\ -\ β$.


Given:

$α$  and  $β$  are the zeros of the quadratic polynomial  $f(x)\ =\ ax^2\ +\ bx\ +\ c$.


To do:

We have to find the value of $α\ -\ β$.


Solution:

The given quadratic equation is $ax^2+bx+c=0$, where a, b and c are constants and $a≠0$.

Sum of the roots $= α+β = \frac{-b}{a}$.

Product of the roots $= αβ = \frac{c}{a}$.

We know that,

$ ( \alpha -\beta )^{2} =( \alpha +\beta )^{2} -4\alpha \beta$

                           

                          $=\left( -\frac{b}{a}\right)^{2} -4\left(\frac{c}{a}\right)$

                         $=\frac{b^{2}}{a^{2}} -\frac{4c}{a}$

                         $=\frac{b^{2} -4ac}{a^{2}}$

$( \alpha -\beta ) =\sqrt{\frac{b^{2} -4ac}{a^{2}}}$

 

                        $=\frac{\sqrt{b^{2} -4ac}}{a}$


The value of $α-β$ is $\frac{\sqrt{b^{2} -4ac}}{a}$.

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Updated on: 10-Oct-2022

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