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"The product of three binomials, just like the product of two, can be found with repeated

applications of the distributive property.
(a) Find the product: (x - 2)(x + 4)(x - 7) . Use area arrays to help keep track of the product.
(b) For what three values of x will the cubic polynomial that you found in part (a) have a value of zero? What famous law is this known as?

1 Answer

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Final answer:

To find the product of three binomials, (x - 2)(x + 4)(x - 7), we can use the distributive property. The result is x^3 - 5x^2 - 22x + 56. To find the three values of x that make the polynomial equal to zero, we solve the equation x^3 - 5x^2 - 22x + 56 = 0. This process involves techniques like factoring and graphing. The law that describes finding the roots of a polynomial equation is the Fundamental Theorem of Algebra.

Step-by-step explanation:

To find the product of (x - 2)(x + 4)(x - 7), we can use the distributive property multiple times.

First, we distribute the first two binomials:

(x - 2)(x + 4) = x(x) + x(4) - 2(x) - 2(4) = x^2 + 4x - 2x - 8 = x^2 + 2x - 8

Next, we distribute the result above with the third binomial:

(x^2 + 2x - 8)(x - 7) = x(x^2) + x(2x) - x(8) - 7(x^2) - 7(2x) + 7(8) = x^3 + 2x^2 - 8x - 7x^2 - 14x + 56 = x^3 - 5x^2 - 22x + 56

Therefore, the product of (x - 2)(x + 4)(x - 7) is x^3 - 5x^2 - 22x + 56.

To find the three values of x that make the cubic polynomial equal to zero, we set the polynomial equal to zero and solve for x:

x^3 - 5x^2 - 22x + 56 = 0

This equation can be solved using various methods such as factoring, graphing, or the Rational Root Theorem.

The famous law that describes finding the roots of a polynomial equation is known as the Fundamental Theorem of Algebra.

User Antoine Grandchamp
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