The zeroes of the polynomial p(x)

Question:

The zeroes of the polynomial $p(x)=3 x^{2}-1$ are

(a) $\frac{1}{3}$ and 3

(b) $\frac{1}{\sqrt{3}}$ and $\sqrt{3}$

(c) $\frac{-1}{\sqrt{3}}$ and $\sqrt{3}$

(d) $\frac{1}{\sqrt{3}}$ and $\frac{-1}{\sqrt{3}}$

 

Solution:

(d) $\frac{1}{\sqrt{3}}$ and $\frac{-1}{\sqrt{3}}$

Let:

$p(x)=3 x^{2}-1$

To find the zeroes of $p(x)$, we have :

$p(x)=0 \Rightarrow 3 x^{2}-1=0$

$\Rightarrow 3 x^{2}=1$

$\Rightarrow x^{2}=\frac{1}{3}$

$\Rightarrow x=\pm \frac{1}{\sqrt{3}}$

$\Rightarrow x=\frac{1}{\sqrt{3}}$ and $x=-\frac{1}{\sqrt{3}}$

Hence, the correct answer is option D.

 

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