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    Hi!

    I am totataly confused with rationalising the denominator and multiplying surds. For example:

    1+√2 x √2

    and...

    3√2
    √8

    also... how would you rationalise this denominator:

    1+√2
    √2

    Arggh Im sooo confused :confused:
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    root 2 times root 2 is simply 2.
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    You can simplify the root 8 to 2 root 2.
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    Or simply change the denominator into

    \frac{3\sqrt 2}{2\sqrt2}

    which then simply becomes

    \frac{3}{2}
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    (Original post by TomLeigh)
    Or simply change the denominator into

    \frac{3\sqrt 2}{2\sqrt2}

    which then simply becomes

    \frac{3}{2}
    How does it become 3/2
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    When you have the same thing as the numerator and the denominator you can just cancel them out, as it is the same as multiplying

    \frac{3}{2}\times \frac{\sqrt2}{\sqrt2}

    which is ultimately the same as \frac{3}{2}\times 1
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    (Original post by TomLeigh)
    When you have the same thing as the numerator and the denominator you can just cancel them out, as it is the same as multiplying

    \frac{3}{2}\times \frac{\sqrt2}{\sqrt2}

    which is ultimately the same as \frac{3}{2}\times 1
    how does 1+√2 x √2 =3
    ???
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    root 2 * root 2
    = root 4
    =2, then add the one
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    Well if you multiply two of the same surds together then you just get the number within the surd. This can also be explained using indices:

    \sqrt3 \times \sqrt3 = 3^\frac{1}{2} \times 3^\frac{1}{2} = 3^1

    As when multiply similar numbers with indices, you add the indices.
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    (Original post by TomLeigh)
    When you have the same thing as the numerator and the denominator you can just cancel them out, as it is the same as multiplying

    \frac{3}{2}\times \frac{\sqrt2}{\sqrt2}

    which is ultimately the same as \frac{3}{2}\times 1

    To be honest, if someone is having problems with surds, that's probably just going to add confusion.
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    (Original post by Sophie Maywood)
    Hi!

    I am totataly confused with rationalising the denominator and multiplying surds. For example:

    1+√2 x √2

    and...

    3√2
    √8

    also... how would you rationalise this denominator:

    1+√2
    √2

    Arggh Im sooo confused :confused:
    1 + √2 x √2
    √2 x √2 = √4
    √4 = 2
    1 + 2 = 3

    3√2
    √8
    √8 = √4 x √2 (look for the largest square number - 4)
    √4 = 2
    3√2
    2√2
    3 (multiply the numerator and denominator by √2)
    2

    1+√2
    √2
    3 (multiply top and bottom by √2)
    2
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    (Original post by TomLeigh)
    Well if you multiply two of the same surds together then you just get the number within the surd. This can also be explained using indices:

    \sqrt3 \times \sqrt3 = 3^\frac{1}{2} \times 3^\frac{1}{2} = 3^1

    As when multiply similar numbers with indices, you add the indices.
    that is just confusing for someone who's not good with surds... all you need to know is that:

    \sqrt a \times \sqrt a = a

    In answer to the thread starter:
    (Original post by Sophie Maywood)
    how does 1+√2 x √2 =3
    ???
    using what i just wrote above
    1+ \sqrt2 \times \sqrt2 = 1+ 2
 
 
 
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