Chap 4 (Recap 2) Let's TALK Algebra before the test ^.^

Let m denote Jane's present age in years.
Write an algebraic expression for each of the following:
(a) Twice Jane's age next year.
(b) Four times Jane's age 3 years ago.
(c) The present age of Jane's mother if her mother is now twice as old as Jane will be 3 years from now.

7 comments:

  1. a) 2(m+1)=2m+2

    b)4(m-3)=4m-12

    c)2(m+3)=2m+6

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  2. a)2 x m+2=2m+2
    b)3 x m-3=3m-3
    c)2 x m+3=2m+3

    ReplyDelete
  3. (a) (m+1) x 2 = 2m + 2
    (b) (m-3) x 4 = 4m - 12
    (c) (m + 3) x 2 = 2m + 6

    JJ(:

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  4. a)2 x m + 2 x 1= 2m+2 years old (ANS)
    b)4 x m+ 4 x 3= 4m+12 years old (ANS)
    c) (m+ 3)2 = 2m +6 years old (ANS)

    ReplyDelete
  5. Here's the complete working and explanation:

    (a)Twice Jane's age next year:
    Next year, Jane's age will be m+1
    So, twice Jane's age will be 2 times (m+1)
    Therefore, 2(m+1) = 2m+2

    (b) Four times Jane's age 3 years ago:
    Jane's age 3 years ago was m-3
    So, four times of that would be 4 times (m-3)
    Therefore, 4(m-3) = 4m-12

    (c) The present age of Jane's mother if her mother is now twice as old as Jane will be 3 years from now:
    Jane's age 3 years from now would be m+3
    Twice as old will be 2 times m+3
    Therefore, 2(m+3) = 2m+6

    1st level working is necessary to show we understand the statement, something like what Jing Jie and Joshua Ma had shown.

    Joshua Loh: Note that you'll have to write down the brackets for m+2, m-3 and m+3. Also check the expressions again.

    ReplyDelete