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Pre-Cal

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Perform the operation and write the result in standard form.

(2-3i)(5i) over 2+3i

Please help!! I do not understand this.

  • Pre-Cal -

    (2-3i)(5i) over 2+3i
    = 5i(2-3i)/(2+3i)
    multiply top and bottom by 2-3i

    = 5i(4 - 12i + 9i^2)/(4-9i^2)
    = 5i(-13 - 12i)/13
    = (-65i - 60i^2)/13
    = (60 - 65i)/13

    or 60/13 - 5i if by standard form you mean a + bi

  • oops arithmetic error Pre-Cal -

    ok, Kim ,I messed up in the arithmetic

    but, if you understand what I did, you should be able to fix it yourself.

    hint: the error is from
    = 5i(4 - 12i + 9i^2)/(4-9i^2) to
    = 5i(-13 - 12i)/13

  • Pre-Cal -

    YOU SHOULD KNOW HOW TO DO THIS!

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