Question

Difficulty: MediumFactoring Polynomials

Determine the missing constants in the completely factored form of the given polynomial.

Answer:The polynomial 5x2−5x−605x^2 - 5x - 60 can be factored completely. When written in the form a(x−b)(x+c)a(x - b)(x + c), where bb and cc are positive integers, the value of aa is 【5】, the value of bb is 【4】, and the value of cc is 【3】.

Answer

The constants are a = 5, b = 4, and c = 3.
The correct values are found by first factoring out the greatest common factor of 55, leaving the quadratic expression x2−x−12x^2 - x - 12. This quadratic expression factors into two binomials by finding two numbers that multiply to −12-12 and add to −1-1, which are −4-4 and 33. This yields the fully factored form 5(x−4)(x+3)5(x - 4)(x + 3). By matching this result to the required algebraic structure a(x−b)(x+c)a(x - b)(x + c), we can directly identify that a=5a = 5, b=4b = 4, and c=3c = 3.

Step-by-Step Solution

1
Find the greatest common factor (GCF) of the terms in the polynomial 5x2−5x−605x^2 - 5x - 60.
The GCF is 55. Factoring it out gives 5(x2−x−12)5(x^2 - x - 12).
Extracting the GCF simplifies the trinomial and makes it easier to factor into binomials.
2
Factor the remaining quadratic trinomial x2−x−12x^2 - x - 12.
We look for two integers that multiply to −12-12 and add to −1-1.
This is the standard procedure for factoring a monic quadratic trinomial of the form x2+bx+cx^2 + bx + c.
3
Identify the proper integers and write the binomial factors.
The integers are −4-4 and 33. The factored trinomial is (x−4)(x+3)(x - 4)(x + 3).
(−4)×3=−12(-4) \times 3 = -12 and −4+3=−1-4 + 3 = -1.
4
Combine the factors and match them to the target form a(x−b)(x+c)a(x - b)(x + c).
The completely factored expression is 5(x−4)(x+3)5(x - 4)(x + 3). Matching this to a(x−b)(x+c)a(x - b)(x + c) yields a=5a = 5, b=4b = 4, and c=3c = 3.
This establishes the precise values corresponding to the blanks in the question.

Key Concept

Factoring out a greatest common factor followed by factoring a quadratic trinomial.
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