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Math Help - GRE - Confused - multiplying Square Roots

  1. #1
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    GRE - Confused - multiplying Square Roots

    If I have (√3 + √5)^2 - How would I multiply this out?

    I keep wanting to get the answer 3 + 8 but the answer in the GRE study book shows 3+2√3√5+5

    Thanks
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  2. #2
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    Hi

    Use formula (a+b) = a + 2 ab + b
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  3. #3
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    running-gag do you mind explaining why it is that formula?

    for instance if I have (x + y)^2 it would be (x + y) (x+ y) = x + xy + xy + y = x+ 2 xy + y is it the same reason?
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  4. #4
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    Quote Originally Posted by lokobreed View Post
    running-gag do you mind explaining why it is that formula?

    for instance if I have (x + y)^2 it would be (x + y) (x+ y) = x + xy + xy + y = x+ 2 xy + y is it the same reason?
    YES
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