Wednesday 11 January 2012

What is wrong?


Question 2
Describe what's wrong with the working and/or answer.
Suggest how it should look like.

16 comments:

  1. Factorissing -9/16n^2 is (3/4n)(3/4n) and not (9/16n)(9/16n) Therefore, when the first step is wrong, the final answer is also incorrect.

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  2. when factorising -9/16n^2 the result should be -(3/4n)(3/4n)
    as a result the rest of the problem is wrong.

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  3. This comment has been removed by the author.

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  4. remember when u square root u need to square root like what u did for 1/4m^2. Similarly, u have to make 9/16n^2 to (3/4n)(3/4n) too.

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  5. (9/16 n)(9/16 n) is not equal to (9/16 n^2). Instead, (3/4n)(3/4n)=9/16n^2 thus, the final answer is also wrong.

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  6. 9/16 is not squared, thus, this is wrong. The student did not square 9/16 as he did with 1/4, thus, this is wrong.

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  7. 9/16n ² ≠ (9/16n x 9/16n)
    9/16n ² = (3/4n x 3/4n)

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  8. 9/16n^2 is not (9/12n), but (3/4n), so it should be -(3/4n)(3/4n)

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  9. 9/16 has not been squared, resulting in a wrong answer.

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  10. The student factories wrongly for -9/16n^2, it should be (3/4n)(3/4n), not (9/16n)(9/16n).

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  11. 9/16 nˆ2 does no equal to (9/16 n)(9/16 n) but instead (3/4n)(3/4n).

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  12. -9/16n2 is not -(9/16n)(9/16n)

    1/4 m2 - 9/16 n2
    = (1/2m)(1/2m) - (3/4n)(3/4n)
    = (1/2m-3/4n)(1/2m+3/4n)

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  13. for the 2nd statement it should be (3/4)2 instead of (9/16)2
    so the rest of the statement is wrong

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  14. Though I'm quite convinced this is my handwriting, I'm ready to redo the question.
    Squareroot 9/16n^2 is not 9/16n*2 , thus the rest of the solution is wrong.

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  15. The student did not find the square root of 9/16 n^2, and therefore got the answer wrong. It should look like this:

    (1/4 m^2)-(9/16 n^2)
    = (1/2 m)^2-(3/4 n)^2
    = (1/2 m-3/4 n)(1/2 m+3/4 n)

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  16. (9/16n)(9/16n) is not equal to 9/16n^2. It should be (3/4n)(3/4n) instead. Thus, the answer would be (1/2m+3/4n)(1/2m-3/4n).

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