Check whether g(x) = 2x² − x + 3 is a factor of f(x) = 6x⁵ − x⁴ + 4x³ − 5x² − x − 15
Given
First polynomial:
g(x) = 2x² − x + 3
Second polynomial:
f(x) = 6x⁵ − x⁴ + 4x³ − 5x² − x − 15
To Check
Whether g(x) is a factor of f(x).
Method
We use the Division Algorithm.
If the remainder is zero, then g(x) is a factor of f(x).
Division Algorithm
f(x) = g(x) × q(x) + r(x)
where degree of r(x) is less than degree of g(x).
Step 1: Divide f(x) by g(x)
6x⁵ − x⁴ + 4x³ − 5x² − x − 15 ÷ (2x² − x + 3)
First Term
6x⁵ ÷ 2x² = 3x³
Multiply:
3x³(2x² − x + 3) = 6x⁵ − 3x⁴ + 9x³
Subtract:
(6x⁵ − x⁴ + 4x³) − (6x⁵ − 3x⁴ + 9x³)
= 2x⁴ − 5x³
Bring down −5x²
2x⁴ − 5x³ − 5x²
Second Term
2x⁴ ÷ 2x² = x²
Multiply:
x²(2x² − x + 3) = 2x⁴ − x³ + 3x²
Subtract:
(2x⁴ − 5x³ − 5x²) − (2x⁴ − x³ + 3x²)
= −4x³ − 8x²
Bring down −x
−4x³ − 8x² − x
Third Term
−4x³ ÷ 2x² = −2x
Multiply:
−2x(2x² − x + 3) = −4x³ + 2x² − 6x
Subtract:
(−4x³ − 8x² − x) − (−4x³ + 2x² − 6x)
= −10x² + 5x
Bring down −15
−10x² + 5x − 15
Fourth Term
−10x² ÷ 2x² = −5
Multiply:
−5(2x² − x + 3) = −10x² + 5x − 15
Subtract:
(−10x² + 5x − 15) − (−10x² + 5x − 15) = 0
Step 2: Write Quotient and Remainder
Quotient, q(x) = 3x³ + x² − 2x − 5
Remainder, r(x) = 0
Final Answer
Since the remainder is zero, therefore
g(x) = 2x² − x + 3 is a factor of f(x).
Conclusion
Hence, the first polynomial divides the second polynomial exactly.