Equations and inequalities with parameters

9000104501

Level: 
A
Consider equation \[ \frac{x - 3} {a} = \frac{a - x} {3} + 2 \] with an unknown \(x\in \mathbb{R}\) and a real parameter \(a\in \mathbb{R}\setminus \{0\}\). Identify a statement which is not true.
For \(a\mathrel{\in }\{ - 3;0\}\) we have \(x = \frac{1} {a+3}\).
For \(a\mathrel{\notin }\{ - 3;0\}\) we have \(x = a + 3\).
If \(a = -3\), then the equation has infinitely many solutions.

9000104503

Level: 
C
Solve the following equation with unknown \(x\) and a real parameter \(a\in\mathbb{R}\). \[\frac{a^{2}(x-1)} {ax-2} = 2\]
\(\begin{array}{cc} \hline \text{Parameter} & \text{Solution set}\\ \hline a=0 & \emptyset \\ a=2 & \mathbb{R}\setminus\{1\} \\ a\notin\{0;2\} & \left\lbrace\frac{a+2}a\right\rbrace \\\hline \end{array}\)
\(\begin{array}{cc} \hline \text{Parameter} & \text{Solution set}\\ \hline a\in\{0;2\} & \mathbb{R} \\ a\notin\{0,2\} & \left\{\frac{a+2}a\right\} \\\hline \end{array}\)
\(\begin{array}{cc} \hline \text{Parameter} & \text{Solution set}\\ \hline a=0 & \emptyset \\ a=2 & \mathbb{R} \\ a\notin\{0;2\} & \left\lbrace\frac{a+2}a\right\rbrace \\\hline \end{array}\)
\(\begin{array}{cc} \hline \text{Parameter} & \text{Solution set}\\ \hline a=0 & \mathbb{R}\setminus\{1\} \\ a=2 & \emptyset \\ a\notin\{0;2\} & \left\lbrace\frac{a+2}a\right\rbrace \\\hline \end{array}\)

9000104504

Level: 
C
Solve the following equation with unknown \(x\) and a real parameter \(a\in\mathbb{R}\setminus\{0\}\). \[\frac{1} {x-a} + 1 = \frac{1} {a}\]
\(\begin{array}{cc} \hline \text{Parameter} & \text{Solution set}\\ \hline a=1 & \emptyset \\ a\notin\{0,1\} & \left\lbrace\frac{a(a-2)}{a-1}\right\rbrace \\\hline \end{array}\)
\(\begin{array}{cc} \hline \text{Parameter} & \text{Solution set}\\ \hline a=1 & \mathbb{R}\setminus\{1\} \\ a\notin\{0;1\} & \left\lbrace\frac{a(a-2)}{a-1}\right\rbrace \\\hline \end{array}\)
\(\begin{array}{cc} \hline \text{Parameter} & \text{Solution set}\\ \hline a=1 & \mathbb{R} \\ a\notin\{0,1\} & \left\lbrace\frac{a(a-2)}{a-1}\right\rbrace \\\hline \end{array}\)

9000104505

Level: 
A
Solve the following equation with unknown \(x\) and a real parameter \(a\in\mathbb{R}\setminus\{-3;3\}\). \[\frac{a-x} {a-3} - \frac{6a} {a^{2}-9} = \frac{x-3} {a+3} \]
\(\begin{array}{cc} \hline \text{Parameter} & \text{Solution set}\\ \hline a=0 & \emptyset \\ a\notin\{-3;0;3\} & \left\lbrace\frac{a^2-9}{2a}\right\rbrace \\\hline \end{array}\)
\(\begin{array}{cc} \hline \text{Parameter} & \text{Solution set}\\ \hline a=0 & \mathbb{R} \\ a\notin\{-3;0;3\} & \left\lbrace\frac{a^2-9}{2a}\right\rbrace \\\hline \end{array}\)
\(\begin{array}{cc} \hline \text{Parameter} & \text{Solution set}\\ \hline a=0 & \mathbb{R}\setminus\{0\} \\ a\notin\{-3;0;3\} & \left\lbrace\frac{a^2-9}{2a}\right\rbrace \\\hline \end{array}\)

9000034704

Level: 
B
Solve the inequality \[ ax - 2 > 0 \] with a real unknown \(x\) and a nonpositive real parameter \(a < 0\).
\(\left (-\infty ; \frac{2} {a}\right )\)
\(\left (-\infty ;-\frac{2} {a}\right )\)
\(\left (\frac{2} {a};\infty \right )\)
\(\left (-\frac{2} {a};\infty \right )\)