Solve the Quadratic Puzzle: Factoring x² - 64

Difference of Squares with Perfect Square Recognition

Fill in the missing element to obtain a true expression:

x264=(x)(+x) x^2-64=(x-_—)(_—+x)

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Complete the missing value
00:13 We'll use the commutative law
00:21 We'll use the abbreviated multiplication formulas
00:37 We'll substitute 64 as B squared
00:47 We'll extract the root to find B
00:52 B is the missing element
00:57 And this is the solution to the question

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Fill in the missing element to obtain a true expression:

x264=(x)(+x) x^2-64=(x-_—)(_—+x)

2

Step-by-step solution

To solve this problem, we need to recognize the expression x264 x^2 - 64 as a difference of squares.

The difference of squares formula states: a2b2=(ab)(a+b) a^2 - b^2 = (a - b)(a + b) .

In this problem, we identify that:

  • a=x a = x

  • b2=64 b^2 = 64 , which means b=64=8 b = \sqrt{64} = 8

Therefore, applying the formula gives us:

x264=(x8)(x+8) x^2 - 64 = (x - 8)(x + 8)

This indicates that the missing element in the expression (x_)(_+x) (x - \_)(\_ + x) is 8 8 .

Thus, the correct answer to fill in the missing element is 8 \boxed{8} , corresponding to choice 4.

3

Final Answer

8

Key Points to Remember

Essential concepts to master this topic
  • Formula: a2b2=(ab)(a+b) a^2 - b^2 = (a - b)(a + b) for difference of squares
  • Recognition: Identify 64=82 64 = 8^2 so x264=x282 x^2 - 64 = x^2 - 8^2
  • Verification: Expand (x8)(x+8)=x264 (x - 8)(x + 8) = x^2 - 64 using FOIL ✓

Common Mistakes

Avoid these frequent errors
  • Confusing the square root of the constant term
    Don't think 64=6 \sqrt{64} = 6 or another wrong value = incorrect factorization! Students often miscalculate basic square roots or confuse 64 with other perfect squares. Always double-check: 8×8=64 8 \times 8 = 64 , so 64=8 \sqrt{64} = 8 .

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 if something is a difference of squares?

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Look for the pattern a2b2 a^2 - b^2 ! Both terms must be perfect squares separated by a minus sign. Here, x2 x^2 and 64=82 64 = 8^2 are both perfect squares.

What if I can't remember which perfect square 64 is?

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Try counting up: 12=1,22=4,32=9,...,82=64 1^2 = 1, 2^2 = 4, 3^2 = 9, ..., 8^2 = 64 . Or work backwards: what number times itself gives 64? Practice memorizing squares 1-12!

Why does the order matter in the factored form?

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It doesn't! (x8)(x+8) (x - 8)(x + 8) equals (x+8)(x8) (x + 8)(x - 8) . But the question format (x_)(_+x) (x - \_)(\_+ x) shows you exactly where to put the 8.

Can I use FOIL to check my answer?

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Absolutely! Expand (x8)(x+8) (x - 8)(x + 8) : First: xx=x2 x \cdot x = x^2 , Outer: x8=8x x \cdot 8 = 8x , Inner: 8x=8x -8 \cdot x = -8x , Last: 88=64 -8 \cdot 8 = -64 . Result: x2+8x8x64=x264 x^2 + 8x - 8x - 64 = x^2 - 64

What's the easiest way to remember the difference of squares formula?

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Think: "square minus square equals difference times sum". The factors are always (ab) (a - b) and (a+b) (a + b) - one subtracts, one adds!

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