Ask questions and get helpful responses.

Algebra

Simplify the expression -5+i/2i

I typed this problem into mathway and they told me the answer was 1/2+5i/2 but wouldn’t show me how they got it. They said to (“multiply by the conjugate and simplify”) but I have no clue on what the conjugate is and how to solve this problem. Can someone help explain better and show me how they came up with that answer please

  1. 👍
  2. 👎
  3. 👁
  4. ℹ️
  5. 🚩
  1. For complex numbers,
    a + bi and a - bi are called "conjugate' complex pairs

    they have the interesting property that if you add them you get the real number 2a
    and if you multiply them , because of the difference of square pattern, you get a^2 - b^2 i^2
    But since i^2 = -1, we end up with a real number as a product.
    e.g. 6 - 5i and 6 + 5i are conjugates of each other
    sum = 6-5i + 6+5i = 12
    product = 36 - 25i^2
    = 36 -(-25) = 61

    Your question is even easier, since the denominator is a monomial instead of a binomial, so we just have to multiply by i/i
    Also I believe, according to the answer, that you have a typo, and you meant
    (-5+i)/(2i)
    = (-5+i)/(2i) *i/i
    = (-5i + i^2)/2i^2)
    = (-5i +i^2)/-2
    = (-5i - 1)/-2
    = (1 + 5i)/2 or they way they have it: 1/2 + 5i/2

    1. 👍
    2. 👎
    3. ℹ️
    4. 🚩
  2. can u guys help me u guys look like ur in college this is my question simplify 8x2.6 im confused im in middle school

    1. 👍
    2. 👎
    3. ℹ️
    4. 🚩
  3. @ who am I?, is your question 8 times 2.6? or 8x(2.6)? or 8x^2.6?

    1. 👍
    2. 👎
    3. ℹ️
    4. 🚩

Respond to this Question

First Name

Your Response

Still need help? You can ask a new question.