According one polynomial determine the values of p and q if(X-1) and (X+2) are factors of 2x³+px²-x+q

Mathematics

ScanSolve AI Answer

Answer

p=5p = \text{5}

q=-6q = \text{-6}

Step-by-step solution

4 steps
  1. Apply the Factor Theorem for the factor (x−1)(x-1).

    The Factor Theorem states that if (x−a)(x-a) is a factor of a polynomial P(x)P(x), then P(a)=0P(a) = 0.
    Given P(x)=2x3+px2−x+qP(x) = 2x^3 + px^2 - x + q and (x−1)(x-1) is a factor, we set x=1x=1:

    P(1)=2(1)3+p(1)2−(1)+q=0P(1) = 2(1)^3 + p(1)^2 - (1) + q = 0 2+p−1+q=02 + p - 1 + q = 0 p+q+1=0p + q + 1 = 0

    This gives our first equation:

    p+q=−1(∗)p + q = -1 \quad (*)
  2. Apply the Factor Theorem for the factor (x+2)(x+2).

    Given (x+2)(x+2) is a factor, we set x=−2x=-2:

    P(−2)=2(−2)3+p(−2)2−(−2)+q=0P(-2) = 2(-2)^3 + p(-2)^2 - (-2) + q = 0 2(−8)+p(4)+2+q=02(-8) + p(4) + 2 + q = 0 −16+4p+2+q=0-16 + 4p + 2 + q = 0 4p+q−14=04p + q - 14 = 0

    This gives our second equation:

    4p+q=14(∗∗)4p + q = 14 \quad (**)
  3. Solve the system of linear equations for pp and qq.

    We have the system:

    1. p+q=−1p + q = -1
    2. 4p+q=144p + q = 14

    Subtract equation (1) from equation (2):

    (4p+q)−(p+q)=14−(−1)(4p + q) - (p + q) = 14 - (-1) 4p+q−p−q=14+14p + q - p - q = 14 + 1 3p=153p = 15 p=153p = \frac{15}{3} p=5p = 5
  4. Substitute the value of pp into equation (1) to find qq.

    Using p+q=−1p + q = -1:

    5+q=−15 + q = -1 q=−1−5q = -1 - 5 q=−6q = -6

    The values are p=5p = \boxed{\text{5}} and q=-6q = \boxed{\text{-6}}.

Was this helpful?

Try one yourself

A new problem that tests the same skill.

Still stuck on this one?

Ask a follow-up, and the answer starts from this question.

Got a different question?Ask your own question
Handwritten step-by-step solution preview

Handwritten Step-by-Step Solution

Get this as a handwritten image on WhatsApp — like a tutor wrote it for you.

Try on WhatsApp