B

9000046609

Level: 
B
Identify an inequality which is true for every \(x\) from the interval \(\left ( \frac{\pi }{4}, \frac{3\pi } {4}\right )\).
\(\sin x\geq \frac{\sqrt{2}} {2} \)
\(\mathop{\mathrm{tg}}\nolimits x > 1\)
\(\cos x > 0\)
\(\mathop{\mathrm{cotg}}\nolimits x\geq \frac{\sqrt{3}} {3} \)

9000046610

Level: 
B
Identify an inequality which is true for every \(x\) from the interval \(\left (\frac{5\pi } {6}, \frac{3\pi } {2}\right )\).
\(\cos x < \frac{1} {2}\)
\(\mathop{\mathrm{tg}}\nolimits x < 0\)
\(\sin x\geq -\frac{\sqrt{2}} {2} \)
\(\mathop{\mathrm{cotg}}\nolimits x < 1\)

9000063101

Level: 
B
Differentiate the following function. \[ f(x) = \frac{x^{2} - 1} {x^{2} + 1} \]
\(f'(x) = \frac{4x} {(x^{2}+1)^{2}} ,\ x\in \mathbb{R}\)
\(f'(x) = \frac{-4x} {x^{2}+1},\ x\in \mathbb{R}\)
\(f'(x) = \frac{4x^{3}} {(x^{2}+1)^{2}} ,\ x\in \mathbb{R}\)
\(f'(x) = \frac{4x} {x^{2}+1},\ x\in \mathbb{R}\)

9000063104

Level: 
B
Differentiate the following function. \[ f(x)= \frac{\sin x} {\sin x -\cos x} \]
\(f'(x) = \frac{-1} {(\sin x-\cos x)^{2}} ,\ x\neq \frac{\pi }{4} + k\pi ,k\in \mathbb{Z}\)
\(f'(x) = \frac{\sin ^{2}x-\cos ^{2}x} {(\sin x-\cos x)^{2}} ,\ x\neq \frac{\pi }{4} + k\pi ,k\in \mathbb{Z}\)
\(f'(x) = \frac{\sin x(\cos x+1)} {(\sin x-\cos x)^{2}} ,\ x\neq \frac{\pi }{4} + k\pi ,k\in \mathbb{Z}\)
\(f'(x) = \frac{\cos ^{2}x-\sin ^{2}x} {(\sin x-\cos x)^{2}} ,\ x\neq \frac{\pi }{4} + k\pi ,k\in \mathbb{Z}\)