If $f(x) = \sin x - \cos x$, $x \in [0, 2\pi]$ then (A) $f(x)$ is increasing in $(0, \frac{3\pi}{4})$ (B) $f(x)$ is decreasing in $(0, \frac{3\pi}{4})$ (C) $f(x)$ is decreasing in $(\frac{3\pi}{4}, \frac{7\pi}{4})$ (D) $f(x)$ is decreasing in $(\frac{7\pi}{4}, 2\pi)$ Choose the correct answer from the options given below:

The approximate volume of a cube of side a meters on increasing the side by 4% is:

The tangent to the curve $y^2 + 2x - 5 = 0$ at the point (h, k) is parallel to the line $x + 2y = 4$, then the value of 'k' is:

The function $f(x) = 6(2x^4 - x^2)$ is strictly increasing in

The interval on which the function $f(x) = x^3 + 2x^2 - 1$ is decreasing, is

Function $f(x) = x + \frac{1}{x}, x \neq 0$ is increasing in the interval

The function, $f(x) = x - \frac{1}{x}$ is