## anonymous one year ago simplify: 3i/2+5i

1. anonymous

$\frac{ 3i}{ 2+5i }$

2. ganeshie8

Multiply both numerator and denominator by the conjugate of denominator

3. anonymous

$\frac{ 3i (2-5i) }{ 2+5i(2-5i) }$ kind of like that right? Just not all over the fraction bar if you know what i mean...

4. ganeshie8

Yes, if you mean : $$\dfrac{ 3i (2-5i) }{ (2+5i)(2-5i) }$$

5. anonymous

you're multiplying them right?

6. ganeshie8

right

7. ganeshie8

for denominator you may use the identity: $$(a+bi)(a-bi)=a^2+b^2$$

8. anonymous

ok, i understand how to get the top part. you multiply 3i and 2 to get 6i, and 3i and 5i to get 15, and because of the i on both, im pretty sure that it ccancels out. the bottom is where i always get lost

9. anonymous

oh i see thank you