Solve for X: Square with Area 16 and Side Length (x+2)

Area Formulas with Algebraic Side Expressions

In front of you is a square.

The expressions listed next to the sides describe their length.

( x>2 x>-2 length measurements in cm).

Since the area of the square is 16.

Find the lengths of the sides of the square.

161616x+2x+2x+2

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1

Understand the problem

In front of you is a square.

The expressions listed next to the sides describe their length.

( x>2 x>-2 length measurements in cm).

Since the area of the square is 16.

Find the lengths of the sides of the square.

161616x+2x+2x+2

2

Step-by-step solution

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

  • Step 1: Set up the equation using the area of the square.
  • Step 2: Solve for x x using algebraic methods.
  • Step 3: Validate the solution against the given condition.

Now, let's work through each step:
Step 1: Given that the area of the square is 16, we use the area formula: (x+2)2=16(x+2)^2 = 16.
Step 2: Solving the equation, take the square root of both sides:
x+2=±4 x + 2 = \pm 4 This produces two solutions: x+2=4orx+2=4 x + 2 = 4 \quad \text{or} \quad x + 2 = -4 Step 3: Solve each equation for x x :
For x+2=4 x + 2 = 4 , we have: x=42=2 x = 4 - 2 = 2 For x+2=4 x + 2 = -4 , we have: x=42=6 x = -4 - 2 = -6 Since x>2 x > -2 , we discard the solution x=6 x = -6 because it does not satisfy the condition.
Thus, the acceptable value is x=2 x = 2 .

The length of the sides of the square is x+2=2+2=4 x + 2 = 2 + 2 = 4 cm.

Therefore, the solution to the problem is 4, and it matches with choice 1.

3

Final Answer

4

Key Points to Remember

Essential concepts to master this topic
  • Area Formula: For a square, area equals side length squared
  • Technique: Set up equation (x+2)2=16 (x+2)^2 = 16 , then take square root
  • Check: Verify x = 2 satisfies x > -2 and gives side = 4 cm ✓

Common Mistakes

Avoid these frequent errors
  • Forgetting to check the domain condition
    Don't ignore the constraint x > -2 when solving = accepting invalid solutions! This leads to impossible negative side lengths. Always verify your x-value satisfies all given conditions before finding the final side length.

Practice Quiz

Test your knowledge with interactive questions

Find the value of the parameter x.

\( 2x^2-7x+5=0 \)

FAQ

Everything you need to know about this question

Why do I get two solutions when taking the square root?

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When you solve (x+2)2=16 (x+2)^2 = 16 , taking the square root gives both positive and negative solutions: x+2 = ±4. This is because both 4² and (-4)² equal 16!

How do I know which solution to keep?

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Check the given condition x > -2. Since x = -6 doesn't satisfy this constraint, we reject it. Only x = 2 is valid because it gives a positive side length.

What if I forgot the constraint and used x = -6?

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Using x = -6 would give a side length of -6 + 2 = -4 cm. Since length cannot be negative, this proves the solution is physically impossible!

Can I solve this without expanding the square?

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Yes! Since (x+2)2=16 (x+2)^2 = 16 , you can directly take the square root: x+2=±16=±4 x+2 = ±\sqrt{16} = ±4 . This saves time compared to expanding to x2+4x+4=16 x^2 + 4x + 4 = 16 .

How do I check my final answer?

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Substitute back: if x = 2, then side length = 2 + 2 = 4 cm. Check the area: 4² = 16 ✓ This matches the given area!

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