Q20. Factor each polynomial.x2-4x-21... [FREE SOLUTION]

91影视

Algebra 1

Carter, Cuevas, Day, Holiday, Luchin

$Math Studyset 91影视 Explanations$ Math

Student Edition 路 801 pages

ISBN: 9780078884801

Chapter 8: Q20. (page 492)

Factor each polynomial.
$x^{2} - 4 x - 21$

Short Answer

Expert verified

The factors of the given polynomial are $(x + 3) (x - 7)$ .

Step by step solution

Step 1. Compare.

Compare a given trinomial to $a x^{2} + b x + c$ and write the values of $a, b$ and role="math" localid="1647519883705" $c$ .

$a = 1 b = 鈭� 4 c = 鈭� 21$

Step 2. List the factors.

List the factors of $鈭� 21$ , where one factor of each pair is negative. Look for the pair of factors with a sum of $鈭� 4$ .

Factors of $- 21$	Sum of factors
$1, - 21$	$鈭� 20$
$3, 鈭� 7$	$- 4$

Therefore, the correct factors are 3 and $- 7$ .

Step 3. Apply factoring pattern of ax2+bx+c.

There are two numbers having product of $鈭� 21$ and sum of $- 4$ . The numbers are 3 and $- 7$ .

role="math" localid="1647520367081" $x^{2} 鈭� 4 x 鈭� 21 = (x + m) (x + p) = (x + 3) (x 鈭� 7)$

Therefore, the factors of $x^{2} 鈭� 4 x 鈭� 21$ are $(x + 3) (x 鈭� 7)$ .

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91影视

Factor each polynomial.
$x^{2} - 4 x - 21$

Short Answer

Step by step solution

Step 1. Compare.

Step 2. List the factors.

Step 3. Apply factoring pattern of ax2+bx+c.

One App. One Place for Learning.

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