Chapter 3: Problem 7
Find the quotient and remainder if \(f(x)\) is divided by \(p(x)\). $$f(x)=10 x+4 ; \quad p(x)=2 x-5$$
Short Answer
Expert verified
Quotient is 5 and remainder is 29.
Step by step solution
01
Set up the division
First, we'll write the division in a polynomial long division format:\[ \frac{10x + 4}{2x - 5} \] This sets up our format for polynomial division, where \(f(x) = 10x + 4\) and \(p(x) = 2x - 5\).
02
Find the first term of the quotient
Divide the leading term of \(f(x)\), which is \(10x\), by the leading term of \(p(x)\), which is \(2x\). \[ \frac{10x}{2x} = 5 \]So, the first term of our quotient is 5.
03
Multiply and subtract
Multiply \(5\) by the entire divisor \((2x - 5)\):\[ 5 \times (2x - 5) = 10x - 25 \]Subtract the result from \(10x + 4\):\[ (10x + 4) - (10x - 25) = 29 \] So we subtract to find the remainder, and our polynomial becomes the constant 29.
04
Write the quotient and remainder
The quotient obtained is 5 and the remainder is 29. Since the degree of the remainder (a constant) is less than the degree of the divisor \((2x - 5)\), we have completed the division with:\[ f(x) = (2x - 5)(5) + 29 \]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Quotient and Remainder
When dividing polynomials, the outcome is expressed in terms of a quotient and a remainder. This is similar to the division you might do with whole numbers but adapted to work with polynomials.
This expression captures the division perfectly, where: - \(5\) is the quotient,- \(29\) is the remainder.
- The quotient is the result of dividing the polynomials, excluding the leftover part (remainder).
- The remainder is what is left over after the division process is completed - it has a lower degree than the divisor.
This expression captures the division perfectly, where: - \(5\) is the quotient,- \(29\) is the remainder.
Polynomial Long Division
Polynomial long division is a systematic method used to divide one polynomial by another. It follows steps remarkably similar to long division of numbers. Here's how it works:
- Setup: Arrange the polynomials to identify the dividend and the divisor. In our example, \(f(x) = 10x + 4\) is the dividend and \(p(x) = 2x - 5\) is the divisor.
- Divide: Compare the leading term of the dividend with the leading term of the divisor. Here we divide \(10x\) by \(2x\) to get \(5\), the first term of our quotient.
- Multiply: Multiply the entire divisor by the first term obtained. So, \(5\times(2x - 5)\) results in \(10x - 25\).
- Subtract: Subtract the product from the original dividend to simplify. \[(10x + 4) - (10x - 25) = 29\]
- The result shows what remains, which is the remainder.
Degree of a Polynomial
Understanding the degree of a polynomial is crucial when performing polynomial division. The degree indicates the highest power of the variable present in the polynomial. Why should we care?
- The degree is key to defining when the division process is complete. For division, when your remainder’s degree is less than that of the divisor, division is finished.
- In our example: The divisor \(2x - 5\) is a polynomial of degree \(1\) (because the highest power of \(x\) is \(x^1\)), and our remainder \(29\) is a constant (having degree \(0\)).