Power and radical functions

9000025804

Level: 
B
In the following list identify a true statement on the function \(f\). \[ f(x) = (x + 1)(x + 2)(x - 3) \]
The function \(f\) is positive on \(I_{1} = (-2;-1)\) and \(I_{2} = (3;\infty )\).
The function \(f\) is an increasing function (in its whole domain).
The function is decreasing only on \(I = (-1;3)\).
The function is decreasing on \(I_{1} = (-\infty ;-2)\) and \(I_{2} = (3;\infty )\).

1003159201

Level: 
C
The 3D printer prints a solid \( 5 \) centimetre cube in \( 2 \) hours. The printer can print the cube with the maximum edge length of \( 20\,\mathrm{cm} \). Suppose the printing time is directly proportional to the cube volume. Choose the function that describes the dependence of the number \( n \) of cubes printed in \( 1 \) day on the printed cube edge length \( a \), which is specified in centimetres. Neglect time needed for using the printer.
\( n=1500a^{-3};\ a\in(0;20] \)
\( n=60a^{-1};\ a\in(0;20] \)
\( n=300a^{-2};\ a\in(0;20] \)
\( n=2.4a;\ a\in(0;20] \)

2010014804

Level: 
C
Find the true statement about the function \( f(x)=\left|x^4-1\right| \).
The function \( f \) has the minima at \( x=-1 \) and \( x=1 \).
The function \( f \) has no minimum.
The function \( f \) has the minimum at \( x=0 \).
The function \( f \) has the minima at \( x=-1 \), \(x=0\) and \( x=1 \).