Question no.8

$7-4 + 9 - 2= 10$

7x4 - 2x9 = 10

7+2+4-sqrt(9)

(9+7+4)/2 means the answer is "Yes"

$10 = ! \left( \frac 4 2 \right) \cdot 7 + \sqrt {9}$

$10 = \frac {\sqrt{4}}{2} \cdot 7 + \sqrt{9}$

$10 = \exp \left( \sqrt{4} - 2 \right) + 7 + \sqrt{9}$

$10 = \sin \left( (4+2)!^\circ \right) + 7 + \sqrt{9}$

$10 = \cos \left( (4+2)!^\circ \right) \cdot 7 + \sqrt{9}$

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$!n$ denotes the subfactorial .

$\exp(x)$ denotes the exponential function $e^x$ .

$\sin x, \cos x$ are the sine and cosine .

$7\times4 - 2 \times 9 = \boxed{10}$