Correctness of my equation relative to the standard given in the text

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Homework Help Overview

The discussion revolves around polynomial division, specifically dividing a polynomial P(x) by a divisor D(x) and expressing the result in a specific form. The original poster presents a polynomial P(x) = 4x^2 - 3x - 7 and a divisor D(x) = 2x - 1, and seeks clarification on the correctness of their solution involving synthetic division.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the requirement that the degree of the remainder R(x) must be less than the degree of the divisor D(x). Questions arise regarding the use of synthetic division for this problem and whether long division is more appropriate. The original poster expresses confusion about the form of the remainder.

Discussion Status

The discussion is active, with participants providing insights into the requirements for polynomial division and clarifying the nature of the remainder. Some participants suggest that the original poster's approach may not align with standard practices, while others offer alternative perspectives on the division process.

Contextual Notes

There is an indication that the original poster may have misunderstood the application of synthetic division versus long division in this context. Additionally, the discussion touches on the nature of remainders in polynomial division, suggesting a need for further exploration of these concepts.

GOPgabe
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Homework Statement



Given a polynomial P(x) and a divisor D(x), divide P(x) by D(x) and return the answer in the form P(x)/D(x) = Q(x) + R(x)/D(x)

In this case: P(x) = 4x^2 - 3x - 7
D(x) = 2x -1

Homework Equations



The one given above

The Attempt at a Solution



I solved the problem using synthetic division and ascertained: P(x)/D(x) = 2x - (x + 7)/(2x - 1)

It's part of a summer engineering program. The TA, however, counted this wrong. Could somebody tell me what the heck the problem with it is? I mean, I checked with wolfram, and evidently this is right. But... I guess not! Help is much appreciated. :)
 
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The degree of R(x) has to be smaller than the degree of D(x). Since the degree of D(x) is 1, then R(x) has to be a constant.

Also, how did you use synthetic division for this problem? Synthetic division is normally used when D(x) is in the form x - c (c being a number).
 
Your "remainder", (-x- 7)/(2x- 1) can be further divided: -(1/2)- (13/2)/(2x-1)
 
That looks absolutely terrible in terms of written form, but alright. I thought R(x) had to be a function containing x. I see now. Thanks. Oh and sorry i meant long division, I posted that around 1 last night. Haha
 
GOPgabe said:
That looks absolutely terrible in terms of written form, but alright. I thought R(x) had to be a function containing x. I see now. Thanks. Oh and sorry i meant long division, I posted that around 1 last night. Haha

Remember f(x) = 4 is a perfectly valid function in terms of x. Just because the function notation has a variable in it does not mean it HAS to be in the equation just like our constant function or even f(x) = y.

Also the thinking behind the remainder comes from number division. Say you are dividing 10 by 3. You wouldn't say that 3 goes into 10 twice remainder 4 would you? You don't want your remained to be bigger than your divisor. In this case 3 can go into 10 one more time can't it?

Similarly with polynomials 2x - 1 can go into -x - 7 one more time. It goes in -1/2 more times.
 

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