Long Division of Polynomials: (10x^3+5x^2-1)/(2x^3-4x^2-x+2)
This article will guide you through the process of performing long division with the polynomials (10x³ + 5x² - 1) and (2x³ - 4x² - x + 2).
Setting Up the Problem
- Write the problem in long division format:
____________ 2x³-4x²-x+2 | 10x³ + 5x² - 1
Performing the Division
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Divide the leading term of the dividend (10x³) by the leading term of the divisor (2x³). This gives us 5. Write this above the dividend.
5 ____________ 2x³-4x²-x+2 | 10x³ + 5x² - 1
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Multiply the divisor (2x³ - 4x² - x + 2) by the quotient term (5). This gives us 10x³ - 20x² - 5x + 10. Write this below the dividend.
5 ____________ 2x³-4x²-x+2 | 10x³ + 5x² - 1 10x³ - 20x² - 5x + 10
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Subtract the result from the dividend. Remember to change the signs of the terms you are subtracting.
5 ____________ 2x³-4x²-x+2 | 10x³ + 5x² - 1 10x³ - 20x² - 5x + 10 ----------------- 25x² + 5x - 11
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Bring down the next term of the dividend (-1).
5 ____________ 2x³-4x²-x+2 | 10x³ + 5x² - 1 10x³ - 20x² - 5x + 10 ----------------- 25x² + 5x - 11
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Repeat steps 1-4 until the degree of the remainder is less than the degree of the divisor.
- Divide the leading term of the new dividend (25x²) by the leading term of the divisor (2x³). This gives us 25/(2x).
- Multiply the divisor (2x³ - 4x² - x + 2) by 25/(2x). This gives us (25x² - 50x - 25/2 + 25).
- Subtract this result from the previous remainder.
- Bring down the next term of the dividend (-1).
- Continue this process until the remainder is a constant term.
5 + 25/(2x) ____________ 2x³-4x²-x+2 | 10x³ + 5x² - 1 10x³ - 20x² - 5x + 10 ----------------- 25x² + 5x - 11 25x² - 50x - 25/2 + 25 ------------------------ 55x + 14/2
Result
The final result is: (10x³ + 5x² - 1)/(2x³ - 4x² - x + 2) = 5 + 25/(2x) + (55x + 14/2) / (2x³ - 4x² - x + 2)
This can also be written as: 5 + 25/(2x) + (55x + 7)/(2x³ - 4x² - x + 2)
Remember to always check your answer by multiplying the quotient and the divisor and adding the remainder. This should equal the original dividend.