posted by zana .
$100,000 is divided into two investments with annual returns of 4% and 7.5%. find the amount invested at the lower rate if the total income at the end of the year is $5050?
amount invested at 4% --- x
amount invested at 7.5% -- 100000-x
solve for x:
.04x + .075(100000-x) = 5050
solve for x and express the solution in a+bi form : ix^2-3x+4i=0
You sure this is right?
ix^2 - 3x - 4i = (ix+1)(x-4i)
but that's not what we have.
So, using the good old quadratic formula,
x = (3 ± √5)]/2i