Question
Using factor theorem, show that g(x) is a factor of p(x), when

 $\text{p}(\text{x})=2\sqrt2\text{x}^2+5\text{x}+\sqrt2,$ $\text{g}(\text{x})=\text{x}+\sqrt2$

Answer

 $\text{p}(\text{x})=2\sqrt2\text{x}^2+5\text{x}+\sqrt2,$

By the factor theorem, (x - a) will be factor of p(x) if p(a) = 0.

Here, $\text{f}(-\sqrt{2})=2\sqrt2(-\sqrt2)^2+5(-\sqrt2)+\sqrt2$

$=2\sqrt2\times2-5\sqrt2+\sqrt2$

$=4\sqrt2-5\sqrt2+\sqrt2$

$=5\sqrt2-5\sqrt2=0.$

$\therefore(\text{x}+\sqrt2)$ is a factor of $2\sqrt2\text{x}^2+5\text{x}+\sqrt2.$ 

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