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Math Help - Need some advice on basic algebra

  1. #1
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    Need some advice on basic algebra

    Remove all the grouping symbols. Simplify as you go by evaluating the numbers. Remove the brackets first.

    a) 5−[3−(x−2)] =5−3+(x−2) =2+x−2 =x.

    b) 5−[3−(x+2)] =5−3+(x+2) =2+x+2 =x+4.

    c) −5+[3−(x−2)] =−5+3−(x−2) =−2−x+2 =−x.

    d) 5−[−3−(x+2)] =5+3+(x+2) =8+x+2 =x+10.

    I understand a,b & c

    The rule as I understood it was if the sign before the grouping symbol is + then we remove the grouping symbol and do nothing. If the sign before the grouping symbol is - then we remove the grouping symbol and reverse the sign(s) that where within it. ie −5+3−(x−2) =−2−x+2.

    But in D the first part is 5−[−3−(x+2)] =5+3+(x+2) whereas I work it as

    5-[-3-(x+2)] = 5-3+(x+2) which is apparently incorrect.

    Can somebody please advise me of my error?

    I'm guessing it a sign rule that I forgot. Maybe its just too late and I should go to bed lol

    Thanks.
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  2. #2
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    Re: Need some advice on basic algebra

    Quote Originally Posted by haruchai View Post
    Remove all the grouping symbols. Simplify as you go by evaluating the numbers. Remove the brackets first.

    a) 5−[3−(x−2)] =5−3+(x−2) =2+x−2 =x.

    b) 5−[3−(x+2)] =5−3+(x+2) =2+x+2 =x+4.

    c) −5+[3−(x−2)] =−5+3−(x−2) =−2−x+2 =−x.

    d) 5−[−3−(x+2)] =5+3+(x+2) =8+x+2 =x+10.

    I understand a,b & c

    The rule as I understood it was if the sign before the grouping symbol is + then we remove the grouping symbol and do nothing. If the sign before the grouping symbol is - then we remove the grouping symbol and reverse the sign(s) that where within it. ie −5+3−(x−2) =−2−x+2.

    But in D the first part is 5−[−3−(x+2)] =5+3+(x+2) whereas I work it as

    5-[-3-(x+2)] = 5-3+(x+2) which is apparently incorrect.

    Can somebody please advise me of my error?

    I'm guessing it a sign rule that I forgot. Maybe its just too late and I should go to bed lol

    Thanks.
    - [-3 ... = + 3
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