need help solving complex number

Hedgecutter

U=2-5i

solve 1+6i
u

im getting -33+12i
29 Think I went wrong some where


sorry U should be under 1+6i and 29 under -33+12i

ZorbaTehZ

Assuming by solve, you mean write in the form x+yi

[latex] \displaystyle \frac{1+6i}{2-5i}=\frac{1+6i}{2-5i}\cdot \frac{2+5i}{2+5i}=\frac{2+5i +12i -30}{4+25}=-\frac{28}{29}+\frac{17}{29}i[/latex]

Hedgecutter

ZorbaTehZ wrote: »

Assuming by solve, you mean write in the form x+yi

[latex] \displaystyle \frac{1+6i}{2-5i}=\frac{1+6i}{2-5i}\cdot \frac{2+5i}{2+5i}=\frac{2+5i +12i -30}{4+25}=-\frac{28}{29}+\frac{17}{29}i[/latex]

Sorry new to this but i have to divide 1-6i by u

TheBody

Hedgecutter wrote: »

Sorry new to this but i have to divide 1-6i by u

Do exactly the same as ZorbaTehZ outlined above with [latex]1-6i[/latex] and let us know how you got on.

sigmundv

In this type of problem we utilise 1) the fact that you can multiply by 1 without changing the result and 2) that [latex](a+b)(a-b)=a^2-b^2[/latex], which gets rid of the [latex]i[/latex] in the denominator, since [latex]i^2=-1[/latex].

ifeelill

http://www.youtube.com/watch?v=KPSj4-76eEc