SOLUTION: I have my placement test tomorrow and i have this example test which i can't solve. I need your help. For i=sqrt(-1), if 3i(2+5i)=x+6i, then x=?

Algebra ->  Complex Numbers Imaginary Numbers Solvers and Lesson -> SOLUTION: I have my placement test tomorrow and i have this example test which i can't solve. I need your help. For i=sqrt(-1), if 3i(2+5i)=x+6i, then x=?      Log On


   

Question 309266: I have my placement test tomorrow and i have this example test which i can't
solve. I need your help.
For i=sqrt(-1), if 3i(2+5i)=x+6i, then x=?
Found 2 solutions by Earlsdon, scott8148:
Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
Solve for x:
3i%282%2B5i%29+=+x%2B6i Simplify the right side by multiplying.
6i%2B15i%5E2+=+x%2B6i Substitute i%5E2+=+-1
6i%2B%2815%29%28-1%29+=+x%2B6i Subtract 6i from both sides.
-15+=+x so...
highlight%28x+=+-15%29

Answer by scott8148(6628) About Me  (Show Source):
You can put this solution on YOUR website!
distributing ___ 6i + 15i^2 = x + 6i

subtracting 6i ___ 15i^2 = x ___ 15(-1) = x ___ -15 = x



good luck on the test