Examples with solutions for Equations with Absolute Values: System of equations

Exercise #1

{∣x+3∣=∣2x+6∣∣x∣=3 \begin{cases} |x+3|=|2x+6| \\ \lvert x\rvert=3 \end{cases}

Video Solution

Step-by-Step Solution

To solve this system of equations, we will follow these steps:

  • Step 1: Solve the second equation ∣x∣=3 |x| = 3 .
  • Step 2: Check both potential solutions from Step 1 in the first equation ∣x+3∣=∣2x+6∣ |x+3| = |2x+6| .

Now, let's work through each step:
Step 1: Solve ∣x∣=3 |x| = 3 . This gives us two potential solutions: x=3 x = 3 and x=−3 x = -3 .

Step 2: Check these solutions in ∣x+3∣=∣2x+6∣ |x+3| = |2x+6| :
- For x=3 x = 3 :
∣x+3∣=∣3+3∣=∣6∣=6|x+3| = |3+3| = |6| = 6 and ∣2x+6∣=∣2(3)+6∣=∣6+6∣=∣12∣=12|2x+6| = |2(3)+6| = |6+6| = |12| = 12.
Since 6≠12 6 \neq 12 , x=3 x = 3 does not satisfy the first equation.

- For x=−3 x = -3 :
∣x+3∣=∣−3+3∣=∣0∣=0|x+3| = |-3+3| = |0| = 0 and ∣2x+6∣=∣2(−3)+6∣=∣−6+6∣=∣0∣=0|2x+6| = |2(-3)+6| = |-6+6| = |0| = 0.
Both sides equal 0, so x=−3 x = -3 satisfies the first equation.

Therefore, the solution to the system of equations is x=−3 x = -3 .

Answer

x=−3 x=-3

Exercise #2

{∣x+2∣=∣x−2∣x4=0 \begin{cases} |x+2|=|x-2| \\ x^4=0 \end{cases}

Video Solution

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Solve the polynomial equation x4=0 x^4 = 0 .
  • Step 2: Verify the solution against the absolute value equation ∣x+2∣=∣x−2∣ |x+2| = |x-2| .
  • Step 3: Ensure the solution matches a provided choice, if necessary.

Now, let's work through each step:

Step 1: Solving x4=0 x^4 = 0 yields x=0 x = 0 , as any non-zero values to the power of 4 would not equal zero.

Step 2: Substituting x=0 x = 0 into the absolute value equation:

∣0+2∣=∣0−2∣ |0+2| = |0-2|

∣2∣=∣−2∣ |2| = |-2|

2=2 2 = 2 , thus the condition is satisfied.

Step 3: Compare with provided answer choices. Since the correct choice must satisfy both equations, x=0 x = 0 is consistent with option (1).

Therefore, the solution to the problem is x=0 x = 0 .

Answer

x=0 x=0

Exercise #3

{∣∣x−11∣−1∣=5x>10 \begin{cases} ||x-11|-1|=5 \\ x>10 \end{cases}

Video Solution

Step-by-Step Solution

To solve the given problem, let's break it down into manageable steps:

The given equation is ∣∣x−11∣−1∣=5 ||x-11|-1|=5 and the condition is x>10 x > 10 .

Step 1: Solve the outer absolute value: ∣∣y∣−1∣=5 ||y|-1|=5 , where y=x−11 y = x - 11 .

This implies two scenarios:

  • ∣y∣−1=5  ⟹  ∣x−11∣=6|y|-1 = 5 \implies |x-11| = 6
  • ∣y∣−1=−5  ⟹  ∣x−11∣=−4|y|-1 = -5 \implies |x-11| = -4 (which is not possible since absolute values are non-negative)

So, we only consider ∣x−11∣=6 |x-11| = 6 .

Step 2: Solve the equation ∣x−11∣=6 |x-11| = 6 , giving two possibilities:

  • x−11=6  ⟹  x=17x - 11 = 6 \implies x = 17
  • x−11=−6  ⟹  x=5x - 11 = -6 \implies x = 5

Step 3: Apply the condition x>10 x > 10 .

Out of the two possible solutions, x=5 x = 5 does not satisfy x>10 x > 10 .

Therefore, the only valid solution that satisfies both conditions is x=17 x = 17 .

The final solution is x=17 x = 17 .

Answer

x=17 x=17

Exercise #4

{∣x+4∣=∣2x+20∣x>−10 \begin{cases} |x+4|=|2x+20| \\ x> -10 \end{cases}

Video Solution

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Consider the equation ∣x+4∣=∣2x+20∣ |x+4| = |2x+20| .
  • Step 2: Break it down into two separate cases.

We'll address each case separately below:

Case 1: x+4=2x+20 x + 4 = 2x + 20

Simplifying gives:

x+4=2x+20 x + 4 = 2x + 20
4=2x−x+20 4 = 2x - x + 20
4=x+20 4 = x + 20
Subtracting 20 from both sides, we get:
x=4−20 x = 4 - 20
x=−16 x = -16 .

Since x>−10 x > -10 is required, x=−16 x = -16 is not valid.

Case 2: x+4=−(2x+20) x + 4 = -(2x + 20)

Simplifying gives:

x+4=−2x−20 x + 4 = -2x - 20
Add 2x 2x to both sides:
x+2x+4=−20 x + 2x + 4 = -20
3x+4=−20 3x + 4 = -20
Subtract 4 from both sides:
3x=−24 3x = -24
Divide by 3:
x=−8 x = -8 .

Check: Since −8>−10-8 > -10, this solution is valid.

Thus, the solution to the problem is x=−8 x = -8 .

Answer

x=−8 x=-8

Exercise #5

{∣x+4∣=∣2x+20∣x<−10 \begin{cases} |x+4|=|2x+20| \\ x < -10 \end{cases}

Video Solution

Step-by-Step Solution

To solve the given problem, we'll work through these steps:

  • Step 1: Solve the equation ∣x+4∣=∣2x+20∣ |x+4| = |2x+20| .
  • Step 2: Consider the two cases derived from the absolute value equation.
  • Step 3: Apply the condition x<−10 x < -10 to determine the suitable solution.

Step 1: We start by considering the absolute value equation ∣x+4∣=∣2x+20∣ |x+4| = |2x+20| . This gives us two cases to explore:

  • Case 1: x+4=2x+20 x+4 = 2x+20
  • Case 2: x+4=−(2x+20) x+4 = -(2x+20)

Step 2: Solve each case individually:

Case 1:
Solving x+4=2x+20 x+4 = 2x+20 ,
We first subtract x x from both sides to obtain:
4=x+20 4 = x + 20 .
Subtracting 20 from both sides, we get:
x=4−20⇒x=−16 x = 4 - 20 \Rightarrow x = -16 .

Case 2:
Solving x+4=−(2x+20) x+4 = -(2x+20) ,
This simplifies to x+4=−2x−20 x+4 = -2x - 20 .
Adding 2x 2x to both sides, we have:
3x+4=−20 3x + 4 = -20 .
Subtracting 4 from both sides gives:
3x=−24 3x = -24 .
Dividing by 3, we find:
x=−8 x = -8 .

Step 3: Consider the inequality x<−10 x < -10 :

  • Substitute x=−16 x = -16 into the inequality: −16<−10 -16 < -10 is true.
  • Substitute x=−8 x = -8 into the inequality: −8<−10 -8 < -10 is false.

Therefore, the solution that satisfies both the equation and the inequality is x=−16 x = -16 .

Answer

x=−16 x=-16

Exercise #6

{∣x+2∣=∣x−2∣∣x+2∣=0 \begin{cases} |x+2|=|x-2| \\ \lvert x+2\rvert=0 \end{cases}

Video Solution

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Solve the equation ∣x+2∣=0 |x+2| = 0
    This implies x+2=0 x+2 = 0 , hence x=−2 x = -2 .
  • Step 2: Solve the equation ∣x+2∣=∣x−2∣ |x+2| = |x-2| .
    This leads to two cases:
    - Case 1: x+2=x−2 x+2 = x-2 results in 2=−2 2 = -2 , which is false.
    - Case 2: x+2=−(x−2) x+2 = -(x-2) simplifies to 2x=0 2x = 0 , hence x=0 x = 0 .
  • Step 3: Check for intersection of solutions.
    We have solutions x=−2 x = -2 from the first equation and x=0 x = 0 from the absolute value equation.
  • Step 4: Verify if any common x x satisfies both equations.

Substituting x=−2 x = -2 into ∣x+2∣=∣x−2∣ |x+2| = |x-2| , we find that it does not satisfy ∣x−2∣=∣−4∣=4 |x-2| = |-4| = 4 . Therefore, x=−2 x = -2 is not a solution to the system.

Substituting x=0 x = 0 into both equations does not satisfy ∣x+2∣=0 |x+2| = 0 . Therefore, there is no overlap of solutions.

The solution to the system is No solution.

Answer

No solution

Exercise #7

{∣∣x−11∣−1∣=5∣x−5∣=0 \begin{cases} ||x-11|-1|=5 \\ |x-5|=0 \end{cases}

Video Solution

Step-by-Step Solution

To solve this system of absolute value equations, we follow these steps:

  • Step 1: Solve the equation ∣x−5∣=0 |x-5|=0 .
  • Step 2: Validate the result with the other equation ∣∣x−11∣−1∣=5 ||x-11|-1|=5 .

Let's work through each step:

Step 1: Solve ∣x−5∣=0 |x-5|=0 .
The equation ∣x−5∣=0 |x-5| = 0 implies that the expression inside the absolute value must be zero. Therefore, x−5=0 x-5=0 gives us:

x=5 x = 5

Step 2: Validate with ∣∣x−11∣−1∣=5 ||x-11|-1|=5 .
Now, substitute x=5 x = 5 into the other equation:

∣5−11∣=∣−6∣=6 |5-11| = | -6 | = 6

∣6−1∣=∣5∣=5 |6-1| = |5| = 5

This simplifies to ∣5∣=5 |5| = 5 , which is true. Therefore, the solution x=5 x = 5 satisfies both equations.

Thus, the system of equations has a single solution: x=5 x = 5 .

Answer

x=5 x=5