Rectangle Dimensions Uncovered: Find the Area When a Side is X + 6

Rectangle Area with Completing the Square

Given a rectangle whose side is greater by 6 than the other side. We mark the area of the rectangle with S

What is the correct argument?

X+6X+6X+6XXX

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:09 First, let's identify the correct statement.
00:13 We'll calculate the area of a rectangle using the formula: length times width.
00:19 Next, we open the parentheses carefully and multiply each factor.
00:33 Then, we add 9.
00:42 Now, let's check if this equals the small side, X, plus 3, all squared.
00:50 We'll use the multiplication formulas to simplify the expression.
00:56 Calculate the multiplication and square it.
01:02 We see both sides are equal.
01:05 And that's how we solve this question!

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Given a rectangle whose side is greater by 6 than the other side. We mark the area of the rectangle with S

What is the correct argument?

X+6X+6X+6XXX

2

Step-by-step solution

To solve this problem, we need to compute the area of the rectangle using its side lengths and check which of the given choices matches this computation.

The rectangle has two sides: the smaller side X X and the larger side X+6 X + 6 . Therefore, the area S S of the rectangle is given by:

S=X(X+6)=X2+6X S = X \cdot (X + 6) = X^2 + 6X

We need to connect this expression for S S with one of the statements describing a relationship involving a shifted value, which most likely involves some manipulations such as transformations. Let's reconsider the given choices.

The choice identified as: 9+S equal to the smaller side plus 3 squared (the two squared). \text{9+S equal to the smaller side plus 3 squared (the two squared).} essentially hints at forming a perfect square that corresponds to a known algebraic identity or transformation.

Notice the expression: X(X+6)=X2+6X X \cdot (X + 6) = X^2 + 6X can be further expanded optionally in known square terms:

=(X+3)29 = (X + 3)^2 - 9

This algebraically transforms the expression for completeness as: (X+3)2=X2+6X+9 (X+3)^2 = X^2 + 6X + 9

This would imply that: S=(X+3)29 S = (X + 3)^2 - 9

Thus adding 9 9 to both sides would align with the choice: 9+S=(X+3)2 9 + S = (X + 3)^2

Therefore, the correct statement that matches this manipulation is:

9+S equal to the smaller side plus 3 squared (the two squared).

3

Final Answer

9+S equal to the smaller side plus 3 squared (the two squared).

Key Points to Remember

Essential concepts to master this topic
  • Formula: Area = length × width = X(X + 6) = X² + 6X
  • Technique: Complete the square: X² + 6X = (X + 3)² - 9
  • Check: Verify 9 + S = (X + 3)² gives the correct relationship ✓

Common Mistakes

Avoid these frequent errors
  • Not recognizing the completing the square pattern
    Don't just leave X² + 6X as the final answer = missing the algebraic transformation! The question asks about a specific relationship involving 9 + S. Always look for ways to complete the square when you see X² + 6X patterns.

Practice Quiz

Test your knowledge with interactive questions

Choose the expression that has the same value as the following:

\( (x+y)^2 \)

FAQ

Everything you need to know about this question

Why do we need to complete the square for this rectangle problem?

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Completing the square helps us transform X2+6X X^2 + 6X into (X+3)29 (X + 3)^2 - 9 , which reveals the relationship 9 + S = (X + 3)² that matches one of the answer choices.

How do I remember the completing the square formula?

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For X2+bX X^2 + bX , take half of the middle coefficient and square it. Here: half of 6 is 3, so we get (X+3)2=X2+6X+9 (X + 3)^2 = X^2 + 6X + 9 .

What does 'the two squared' mean in the answer choice?

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This phrase refers to squaring the entire expression (X + 3). So 'the smaller side plus 3 squared' means (X+3)2 (X + 3)^2 , not X+32 X + 3^2 .

Can I solve this without completing the square?

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Technically yes, but completing the square is the key to matching the given answer choices. The question is testing your ability to recognize and apply this algebraic transformation.

Why is the answer about the smaller side when we're looking at area?

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The area formula S=X(X+6) S = X(X + 6) uses both sides, but when we complete the square, we get (X+3)2 (X + 3)^2 where X is the smaller side, creating the relationship in the correct answer.

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