Rational functions

2000018805

Level: 
A
The test driver drove from Ostrava to Warsaw at an average speed of \(66\, \mathrm{km}/\mathrm{h}\) and the journey took him \(6\) hours. After him, the same route took several other drivers. (Each driver took a different driving time.) Choose the function giving the average speed \(v\) of each of these drivers as a function of the total driving time \(t\) from Ostrava to Warsaw.
\( v=\frac{396}t,\ \ t\in(0;\infty) \)
\( v=\frac{66}t,\ \ t\in(0;\infty) \)
\( v=66 t,\ \ t\in(0;\infty) \)
\( v=\frac{t}{396},\ \ t\in(0;\infty) \)

2000018801

Level: 
A
Consider a triangle with area of \(5\, \mathrm{cm}^{2}\). Find the formula which relates the length of its side \(a\) to the length of the height \(v_a\) , where \(v_a\) is the height to the side \(a\).
\(v_a = \frac{10} {a}\)
\(v_a = \frac{5} {a}\)
\(v_a =5 {a}\)
\(v_a = \frac{5} {2a}\)

2010017305

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 \(k_{2}\)?
\( k_1 < k_2\)
\( k_1 \geq k_2\)
\( k_1 = k_2\)
The relationship between \(k_1\) and \(k_2\) cannot be determined from the picture.

2010017304

Level: 
C
Consider the functions \[ \text{$f(x)= -\frac{2} {3x}$ and $g(x) = \frac{k} {x}$.} \] Identify the value of the coefficient \(k\) which ensures that the graphs of both functions are symmetric about \(y\)-axis.
\( k=\frac23\)
\( k=\frac32\)
\( k=-\frac23\)
\( k=-\frac32\)

2010017302

Level: 
C
Find the interval where the function \(f(x) = -\left |2+\frac{1} {x}\right |\) is a decreasing function. The function \(f\) is graphed in the picture.
\(\left[ -\frac12; 0\right)\)
\((-\infty ;0)\)
\(\left[ -\frac12; \infty\right)\)
\(\left(-\infty ; -\frac12\right)\)