Completing the Expression: Find the Missing Numbers in x^2-36=(x-__)(__+x)

Difference of Squares with Perfect Square Constants

Fill in the missing element to obtain a true expression:

x236=(x)(+x) x^2-36=(x-_—)\cdot(_—+x)

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1

Understand the problem

Fill in the missing element to obtain a true expression:

x236=(x)(+x) x^2-36=(x-_—)\cdot(_—+x)

2

Step-by-step solution

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

  • Step 1: Identify the given expression and recognize the form.
  • Step 2: Apply the difference of squares formula.
  • Step 3: Determine the missing element.
  • Step 4: Verify the solution against the possible choices.

Now, let's work through each step:
Step 1: The given expression is x236 x^2 - 36 . This resembles a difference of squares, which is a2b2 a^2 - b^2 .
Step 2: Recognize that x2 x^2 represents a2 a^2 and 36 36 represents b2 b^2 .
Step 3: Find b b such that b2=36 b^2 = 36 . This gives b=6 b = 6 because 62=36 6^2 = 36 .
Step 4: The difference of squares formula states a2b2=(ab)(a+b) a^2 - b^2 = (a - b)(a + b) . So we rewrite x236 x^2 - 36 as (x6)(x+6) (x - 6)(x + 6) .

Therefore, the missing element that makes the expression true is 6 6 .

3

Final Answer

6

Key Points to Remember

Essential concepts to master this topic
  • Pattern Recognition: Identify a2b2 a^2 - b^2 form where both terms are perfect squares
  • Formula Application: Use a2b2=(ab)(a+b) a^2 - b^2 = (a-b)(a+b) with x236=(x6)(x+6) x^2 - 36 = (x-6)(x+6)
  • Verification Check: Expand (x6)(x+6)=x236 (x-6)(x+6) = x^2 - 36 to confirm correctness ✓

Common Mistakes

Avoid these frequent errors
  • Finding square root of coefficient incorrectly
    Don't assume the missing number is 36 because that's what you see = (x36)(36+x) (x-36)(36+x) gives x21296 x^2 - 1296 ! You need the square root of 36, not 36 itself. Always find b2 \sqrt{b^2} to get the correct factorization.

Practice Quiz

Test your knowledge with interactive questions

Solve:

\( (2+x)(2-x)=0 \)

FAQ

Everything you need to know about this question

How do I know this is a difference of squares?

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Look for the pattern a2b2 a^2 - b^2 where both terms are perfect squares separated by subtraction. Here, x2 x^2 and 36=62 36 = 6^2 fit this pattern perfectly!

Why is the answer 6 and not 36?

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Because 36=62 36 = 6^2 , so we need the square root of 36, which is 6. The difference of squares formula uses a a and b b , not a2 a^2 and b2 b^2 in the factored form.

What if I can't recognize perfect squares quickly?

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Practice common perfect squares: 1, 4, 9, 16, 25, 36, 49, 64, 81, 100. For larger numbers, try taking the square root - if you get a whole number, it's a perfect square!

How do I check my factorization is correct?

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Use FOIL to expand your answer: (x6)(x+6)=x2+6x6x36=x236 (x-6)(x+6) = x^2 + 6x - 6x - 36 = x^2 - 36 . The middle terms cancel out, giving you back the original expression!

Does the order of factors matter?

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No! (x6)(x+6) (x-6)(x+6) and (x+6)(x6) (x+6)(x-6) are equivalent due to the commutative property of multiplication. Both expand to the same expression.

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