If a polynomial 8x4-8x3-18x2-px-q is exactly divisible by 4x2-4x+1 find value of p and q
Can anyone do this without long division....
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Answers
Given,
8x⁴ - 8x³ - 18x² - px - q is exactly divisible by 4x² - 4x + 1.
To find,
The value of p and q.
8x⁴ - 8x³ - 18x² - px - q is exactly divisible by 4x² - 4x + 1.
⇒4x² - 4x + 1 is a factor of 8x⁴ - 8x³ - 18x² - px - q.
⇒(2x - 1)² is a factor of 8x⁴ - 8x³ - 18x² - px - q.
so, (2x - 1) is a factor of 8x⁴ - 8x³ - 18x² - px - q.
so, 1/2 is a zero of given polynomial, 8x⁴ - 8x³ - 18x² - px - q..
so, 8(1/2)⁴ - 8(1/2)³ - 18(1/2)² - p(1/2) - q = 0
⇒1/2 - 1 - 9/2 - p/2 - q = 0
⇒-5 - p/2 - q = 0
⇒p + 2q + 10 = 0......(1)
now, 8x⁴ - 8x³ - 18x² - px - q
= 2x²(4x² - 4x + 1) - 20x² - px - q
= 2x² (4x² - 4x + 1) - 5(4x² + px/5 + q/5)
is 8x⁴ - 8x³ - 18x² - px - q exactly divisible by 4x² - 4x + 1 ?
then, 4x² + px/5 + q/5 = 4x² - 4x + 1
p = -20 and q = 5
now check equation (1), by putting p = -20 and q = 5.
i.e., -20 + 2 × 5 + 10 = 0
hence, p = -20 and q = 5
Step-by-step explanation:
8x⁴-8x³-18x-px-q divisible by 4x2-4x+1