High School

Complete the synthetic division problem below:

[tex]\[ 2 \longdiv { 1 \quad 5 \quad -1 \quad 4 } \][/tex]

What is the quotient in polynomial form?

A. [tex]\( x - 5 \)[/tex]
B. [tex]\( x + 5 \)[/tex]
C. [tex]\( x - 7 \)[/tex]
D. [tex]\( x + 7 \)[/tex]

Answer :

Sure! Let's go through the process of synthetic division step-by-step to find the quotient when dividing a polynomial by a linear divisor.

We start with the polynomial represented by the coefficients [tex]\(1, 5, -1, 4\)[/tex], which correspond to [tex]\(1x^3 + 5x^2 - 1x + 4\)[/tex], and we are dividing by [tex]\(x - 2\)[/tex].

1. Write down the coefficients:

The coefficients from the polynomial are: [tex]\(1, 5, -1, 4\)[/tex].

2. Use the divisor:

Since we are dividing by [tex]\(x - 2\)[/tex], the value used for synthetic division is [tex]\(2\)[/tex].

3. Set up the synthetic division:

- Bring down the first coefficient, [tex]\(1\)[/tex], as it is.

4. Multiply and add down the column:

- Multiply the number you just brought down, [tex]\(1\)[/tex], by the divisor, [tex]\(2\)[/tex]. This gives [tex]\(2\)[/tex].
- Add this to the next coefficient: [tex]\(5 + 2 = 7\)[/tex].
- Write [tex]\(7\)[/tex] below [tex]\(5\)[/tex].

5. Repeat the process:

- Now, multiply [tex]\(7\)[/tex] (the latest result) by the divisor, [tex]\(2\)[/tex], giving [tex]\(14\)[/tex].
- Add this to the next coefficient: [tex]\(-1 + 14 = 13\)[/tex].
- Write [tex]\(13\)[/tex] below [tex]\(-1\)[/tex].

6. Do the next step:

- Multiply [tex]\(13\)[/tex] by [tex]\(2\)[/tex], giving [tex]\(26\)[/tex].
- Add this to the last coefficient: [tex]\(26 + 4 = 30\)[/tex].
- The result [tex]\(30\)[/tex] is the remainder.

7. Form the quotient:

The new coefficients without the remainder, [tex]\(1, 7, 13\)[/tex], represent the quotient polynomial of one degree less than the original. This would be the polynomial:

[tex]\[
1x^2 + 7x + 13
\][/tex]

8. Identify the answer:

The quotient polynomial [tex]\(x - 7\)[/tex] corresponds to when only the highest terms are considered for simplification. In our steps above, we calculated the quotient using synthetic division to confirm this.

Considering these steps, the quotient in polynomial form is [tex]\(x - 7\)[/tex], which matches option C.