Is this the simplified form of (a + b)^3 - 8c^3?

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In summary, the expression (a + b)^3 - 8c^3 can be rewritten as (a + b)^3 - (2c)^3 by applying the difference of cubes formula. This is because the number 8 can be written as 2^3, which allows us to use the property x^ny^n = (xy)^n.
  • #1
mathdad
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Factor (a + b)^3 - 8c^3.

Is this the difference of cubes?

Formula:

x^3 - a^3 = (x - a)(x^2 + ax + a^2)

Let x = (a + b)

Let a = 8

(a + b - 8)((a + b)^2 + 8(a + b) + 64)

Correct?
 
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  • #2
I would begin by writing the expression as the difference of cubes:

\(\displaystyle (a+b)^3-8c^3=(a+b)^3-(2c)^3\)

Now apply the difference of cubes formula...:D
 
  • #3
Why did you write -8c^3 as -(2c)^3?

The number 8 is not part of c^3.

Are you saying that -8•c^3 = (-8c)^3?
 
  • #4
RTCNTC said:
Why did you write -8c^3 as -(2c)^3?

The number 8 is not part of c^3.

Are you saying that -8•c^3 = (-8c)^3?

I applied the exponential property:

\(\displaystyle x^ny^n=(xy)^n\)

Since $8=2^3$, we can write:

\(\displaystyle 8c^3=2^3c^3=(2c)^3\)
 
  • #5
I got it now.
 

Related to Is this the simplified form of (a + b)^3 - 8c^3?

1. What is the difference of cubes?

The difference of cubes refers to a mathematical expression in the form of (a^3 - b^3), where a and b are any real numbers. It is called a difference because it involves subtracting one cube from another.

2. What is the formula for the difference of cubes?

The formula for the difference of cubes is (a^3 - b^3) = (a - b)(a^2 + ab + b^2). This formula can be used to expand and simplify any expression in the form of (a^3 - b^3).

3. What is the significance of the difference of cubes?

The difference of cubes has various applications in mathematics and science, such as in factoring polynomials, solving equations, and in physics for calculating the work done by a force in moving an object. It also helps in understanding the relationship between different quantities and their differences.

4. How is the difference of cubes different from the sum of cubes?

The difference of cubes and the sum of cubes are two different types of mathematical expressions. The sum of cubes refers to an expression in the form of (a^3 + b^3), where a and b are any real numbers, and it involves adding two cubes. On the other hand, the difference of cubes involves subtracting two cubes.

5. Can the difference of cubes be negative?

Yes, the difference of cubes can be negative. Since the result of the expression (a^3 - b^3) depends on the values of a and b, it can be positive, negative, or zero. For example, if a = 5 and b = 6, the difference of cubes would be -31.

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