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Math Help - Algebra Factorisation and Equations

  1. #1
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    Algebra Factorisation and Equations

    Please help!!! 2 questions.
    Factorise b^2 -16 and Solve for x: (x+1)(x-4)=0
    Can you please show me how to work these out and also show the answer.
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  2. #2
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    Either x+1=0 or x-4=0. Solve these to get x=-1 and x=4.

     <br />
b^2-16=(b-4)(b+4)<br />

    This is obtained from the difference of 2 squares, if you don't know this yet then look it up and learn it.
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  3. #3
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    I understand the factorisation but am having trouble with other one. My daughter seems to think you have to get rid of one of the x's somehow...
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  4. #4
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    No, it is a quadratic which means it has 2 solutions.
    You can divide through by x+1 or by x-4 to get either x+1=0 or x-4=0. Thus x=-1 or x=4.
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