Verify the Equality: (x+8)(x-4) = (x-8)(x+4)

Polynomial Expansion with Coefficient Comparison

Is equality correct?

(x+8)(x4)=(x8)(x+4) (x+8)(x-4)=(x-8)(x+4)

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Are the expressions equal?
00:03 Open parentheses properly, multiply each factor by each factor
00:21 Calculate the products
00:34 Collect terms
00:42 Use the same method and simplify the other side
00:53 Open parentheses properly, multiply each factor by each factor
01:06 Calculate the products and collect terms
01:24 Compare the terms of the expressions, we see they are different
01:28 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

Is equality correct?

(x+8)(x4)=(x8)(x+4) (x+8)(x-4)=(x-8)(x+4)

2

Step-by-step solution

To determine if the equation (x+8)(x4)=(x8)(x+4)(x+8)(x-4) = (x-8)(x+4) is true, we'll need to expand both sides and compare their forms.

We begin with the left-hand side:

  • (x+8)(x4)(x+8)(x-4)

  • Expanding using the distributive property, we get:

  • xx+x(4)+8x+8(4)x \cdot x + x \cdot (-4) + 8 \cdot x + 8 \cdot (-4)

  • This simplifies to x24x+8x32x^2 - 4x + 8x - 32

  • Further simplification gives x2+4x32x^2 + 4x - 32

Now, let's examine the right-hand side:

  • (x8)(x+4)(x-8)(x+4)

  • Expanding using the distributive property, we obtain:

  • xx+x48x84x \cdot x + x \cdot 4 - 8 \cdot x - 8 \cdot 4

  • This simplifies to x2+4x8x32x^2 + 4x - 8x - 32

  • Further simplification yields x24x32x^2 - 4x - 32

Next, compare the results:

The left-hand side is x2+4x32x^2 + 4x - 32, while the right-hand side is x24x32x^2 - 4x - 32.

Note that the coefficients of the xx terms are different:

  • On the left: The coefficient of xx is +4+4.

  • On the right: The coefficient of xx is 4-4.

Since the coefficients ofxx differ, the two expressions are not equal.

Therefore, the equality (x+8)(x4)=(x8)(x+4)(x+8)(x-4) = (x-8)(x+4) is not correct.

The correct answer to this problem is No, the coefficients of x x in contrasting expressions.

3

Final Answer

No, the coefficients of x x In contrasting expressions

Key Points to Remember

Essential concepts to master this topic
  • Expansion Rule: Use distributive property to multiply each term systematically
  • Technique: (x+8)(x4)=x2+4x32 (x+8)(x-4) = x^2 + 4x - 32 vs (x8)(x+4)=x24x32 (x-8)(x+4) = x^2 - 4x - 32
  • Check: Compare coefficients term by term: x2 x^2 , x x , and constant terms ✓

Common Mistakes

Avoid these frequent errors
  • Assuming expressions are equal without expanding
    Don't just look at the structure and assume equality = wrong conclusion! The order of terms matters when multiplying. Always expand both expressions completely and compare each coefficient.

Practice Quiz

Test your knowledge with interactive questions

It is possible to use the distributive property to simplify the expression below?

What is its simplified form?

\( (ab)(c d) \)

\( \)

FAQ

Everything you need to know about this question

Why can't I just rearrange the terms to make them equal?

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You cannot rearrange factors in a product! (x+8)(x4) (x+8)(x-4) and (x8)(x+4) (x-8)(x+4) are completely different expressions that expand to different polynomials.

How do I expand binomial products correctly?

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Use FOIL method: First terms, Outer terms, Inner terms, Last terms. For example: (x+8)(x4)=x24x+8x32 (x+8)(x-4) = x^2 - 4x + 8x - 32 .

What should I compare after expanding?

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Compare each coefficient separately: the x2 x^2 coefficient, the x x coefficient, and the constant term. All three must match for equality.

Why are the x coefficients different here?

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Left side: 4x+8x=+4x -4x + 8x = +4x . Right side: +4x8x=4x +4x - 8x = -4x . The order of the constants (8 vs -8, -4 vs +4) creates opposite signs!

Can two different expressions ever be equal for all x values?

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Only if they're identical after expanding! If any coefficient differs, the expressions are equal only for specific x values, not for all x values.

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