X-3 and 2x-1 are factors of 2x^3-px^2-2qx+q. Find the values of p and q.
1 answer:
Answer:
p =1
q = 9
Step-by-step explanation:
f(x) = 2x³ - px² + 2qx + q
(x - 3) is a factor of f(x)
⇒f(3) = 0
2(3)³ - p*3² - 2q*3 +q = 0
2*27 - 9p - 6q + q = 0
54 - 9p - 5q = 0
-9p - 5q = -54 -------------------(I)
(2x - 1) is a factor of f(x)
2x - 1 = 0
2x = 1

f(1/2) = 0
![2*(\dfrac{1}{2})^{3}-p*(\dfrac{1}{2})^{2}-2q*\dfrac{1}{2}+q=0\\\\2*\dfrac{1}{8}-p*\dfrac{1}{4}-q+q = 0\\\\\dfrac{1}{4}-\dfrac{1}{4}p =0\\\\[Multiply the entire equation by 4]\\\\4*\dfrac{1}{4}-4*\dfrac{1}{4}p=0\\\\](https://tex.z-dn.net/?f=2%2A%28%5Cdfrac%7B1%7D%7B2%7D%29%5E%7B3%7D-p%2A%28%5Cdfrac%7B1%7D%7B2%7D%29%5E%7B2%7D-2q%2A%5Cdfrac%7B1%7D%7B2%7D%2Bq%3D0%5C%5C%5C%5C2%2A%5Cdfrac%7B1%7D%7B8%7D-p%2A%5Cdfrac%7B1%7D%7B4%7D-q%2Bq%20%3D%200%5C%5C%5C%5C%5Cdfrac%7B1%7D%7B4%7D-%5Cdfrac%7B1%7D%7B4%7Dp%20%3D0%5C%5C%5C%5C%5BMultiply%20the%20entire%20equation%20by%204%5D%5C%5C%5C%5C4%2A%5Cdfrac%7B1%7D%7B4%7D-4%2A%5Cdfrac%7B1%7D%7B4%7Dp%3D0%5C%5C%5C%5C)
1 - p = 0
-p = -1
p = 1
Substitute p =1 in equation (I)
-9*1 - 5q = -54
-9 - 5q = -54
-5q = -54 + 9
-5q = -45
q = -45/(-5)
q = 9
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