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How would you complete the square of these two expressions? Watch

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    Can someone please walk me through and explain the process of completing the square of these expressions:

    1) x^2 + 4x -5

    2) x^2 - 20x +10

    Thanks!
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    (Original post by blobbybill)
    Can someone please walk me through and explain the process of completing the square of these expressions:

    1) x^2 + 4x -5

    2) x^2 - 20x +10

    Thanks!
    Do you know where to begin? Have you tried anything?
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    (Original post by RDKGames)
    Do you know where to begin? Have you tried anything?
    I know you halve the co-efficient of X and put it in a bracket, then square the bracket, but I don't know how that would work if one of the signs was negative and another was positive (eg the first question)
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    (Original post by blobbybill)
    I know you halve the co-efficient of X and put it in a bracket, then square the bracket, but I don't know how that would work if one of the signs was negative and another was positive (eg the first question)
    In exactly the same way. Remember that -5 = +(-5) so subtracting a number is the same as adding the negative of it.

    So the first one would be just as you said: x^2+4x-5=x^2+4x+(-5)=(x+2)^2+a+(-5)=(x+2)^2+a-5

    Can you work out a and as a result work out the completed square form from there?
 
 
 
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