Questions: Which of the following equations have exactly one solution?
Choose all answers that apply:
(A) 2x-31=2x-31
(B) 2x-31=-2x-31
c. 2x+31=2x-31
(D) 2x-2=2x-31
Transcript text: Which of the following equations have exactly one solution?
Choose all answers that apply:
(A) $2 x-31=2 x-31$
(B) $2 x-31=-2 x-31$
c. $2 x+31=2 x-31$
(D) $2 x-2=2 x-31$
Solution
Solution Steps
To determine which equations have exactly one solution, we need to analyze each equation to see if it simplifies to a form where \( x \) can be uniquely determined.
For equation (A) \( 2x - 31 = 2x - 31 \), we see that both sides are identical, which means it has infinitely many solutions.
For equation (B) \( 2x - 31 = -2x - 31 \), we can solve for \( x \) to see if it has a unique solution.
For equation (C) \( 2x + 31 = 2x - 31 \), we can solve for \( x \) to see if it has a unique solution.
For equation (D) \( 2x - 2 = 2x - 31 \), we can solve for \( x \) to see if it has a unique solution.
Solution Approach
Simplify each equation and solve for \( x \).
Check if the equation has a unique solution.
Step 1: Analyze Equation (A)
The equation \( 2x - 31 = 2x - 31 \) simplifies to \( x = x \), which is always true for any value of \( x \). Therefore, this equation has infinitely many solutions.
Step 2: Analyze Equation (B)
The equation \( 2x - 31 = -2x - 31 \) can be rearranged as follows:
\[
2x + 2x = 31 - 31 \implies 4x = 0 \implies x = 0
\]
This equation has exactly one solution: \( x = 0 \).
Step 3: Analyze Equation (C)
The equation \( 2x + 31 = 2x - 31 \) simplifies to:
\[
31 = -31
\]
This is a contradiction, meaning there are no solutions for this equation.
Step 4: Analyze Equation (D)
The equation \( 2x - 2 = 2x - 31 \) simplifies to:
\[
-2 = -31
\]
This is also a contradiction, indicating that there are no solutions for this equation.
Final Answer
The only equation that has exactly one solution is (B). Thus, the answer is
\[
\boxed{B}
\]