C

9000009906

Level: 
C
Consider a function \[ f(x) = \frac{k} {x} \] with a nonzero real parameter \(k\). Describe what happens with the function \(f\) if the coefficient \(k\) changes the sign.
The function changes the type of monotonicity on the sets \(\mathbb{R}^{+}\) and \(\mathbb{R}^{-}\) (either from an increasing function into a decreasing function or vice versa).
The function changes its parity (from an odd function into an even function or from an even function into an odd function).
The domain of the function changes.
None of the above, both functions have the same parity, monotonicity and domain.

9000009907

Level: 
C
Consider a function \[ f(x) = \frac{k} {x} \] with a nonzero real parameter \(k\). Suppose that the value of the coefficient \(k\) changes, but the sign of \(k\) remains the same. Describe which of the properties of \(f\) is changed.
None of the above, both functions have the same parity, monotonicity and range.
The function changes its parity (from an odd function into an even function or from en even function into an odd function).
The range of the function changes.
The function changes the type of monotonicity on the sets \(\mathbb{R}^{+}\) and \(\mathbb{R}^{-}\) (either from an increasing function into a decreasing function or vice versa).

9000009901

Level: 
C
The picture shows parts of the graphs of the functions \[ \text{$f(x)= \frac{k_{1}} {x} $ and $g(x) = \frac{k_{2}} {x} $.} \] Find the relationship between \(k_{1}\) and \(k_{2}\)?
\(k_{1} > k_{2}\)
\(k_{1} < k_{2}\)
\(k_{1} = k_{2}\)
No conclusion is possible, more of the above possibilities may occur.

9000010609

Level: 
C
Identify a function which is a possible inverse to the function graphed in the picture.
\(y = x^{-1}\), \(x\in (0;\infty )\)
\(y = x\), \(x\in (0;\infty )\)
\(y = -x\), \(x\in (0;\infty )\)
\(y = -x^{-1}\), \(x\in (0;\infty )\)
\(y = x^{2}\), \(x\in (0;\infty )\)
\(y = -x^{2}\), \(x\in (0;\infty )\)

9000009909

Level: 
C
Consider the system \[\begin{aligned} y & = \frac{k} {x}, & & \\y & = a, & & \end{aligned}\] where \(a\), \(k\) are real parameters and \(x\), \(y\) are real variables. Determine the conditions for \(a\) and \(k\) so that the system has a unique solution in \(\mathbb{R}^{-}\times \mathbb{R}^{-}\).
\(a < 0\) and \(k > 0\)
\(a < 0\) and \(k < 0\)
\(a > 0\) and \(k < 0\)
\(a > 0\) and \(k > 0\)

9000010610

Level: 
C
Identify a function which is a possible inverse to the function graphed in the picture.
\(y = x^{2}\), \(x\in (-\infty ;0] \)
\(y = x^{-2}\), \(x\in (-\infty ;0] \)
\(y = -x^{2}\), \(x\in [ 0;\infty )\)
\(y = x^{\frac{1} {2} }\), \(x\in [ 0;\infty )\)
\(y = -x^{\frac{1} {2} }\), \(x\in [ 0;\infty )\)
\(y = -2x\), \(x\in (-\infty ;0] \)

9000010608

Level: 
C
Identify a function which is a possible inverse to the function graphed in the picture.
\(y = x^{3}\), \(x\in (-\infty ;\infty )\)
\(y = x^{-3}\), \(x\in (-2;2)\)
\(y = x^{\frac{1} {3} }\), \(x\in (0;\infty )\)
\(y = -x^{\frac{1} {3} }\), \(x\in (-\infty ;\infty )\)
\(y = 8x\), \(x\in (-\infty ;\infty )\)
\(y = -4x\), \(x\in (-\infty ;\infty )\)

9000009304

Level: 
C
A tank contains \(1\: 000\) litres of petrol. The petrol escapes at a constant speed \(20\) litres per minute. In what time will there be just \(200\) litres of the petrol in the tank?
\(40\, \mathrm{min}\)
\(10\, \mathrm{min}\)
\(20\, \mathrm{min}\)
\(30\, \mathrm{min}\)