$\sqrt{2 k^{2} + 17} - x = 0$
If $k > 0$ and $x = 7$ in the equation above, what is the value of $k$ ?

2

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Solution

The correct option is B $4$
Given expression is $\sqrt{2 k^{2} + 17} - x = 0$
Given that $x = 7$ , we thus get
$\sqrt{2 k^{2} + 17} = 7$
$∴ 2 k^{2} + 17 = 49$ [squaring both the sides]
$∴ 2 k^{2} = 32$
$∴ k^{2} = 16$
$∴ k = \pm 4$
$⟹ k = 4$ $[∵ k > 0]$

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