A woman has a total of $
15,000
to invest. She invests part of the money in an account that pays
10
%
per year and the rest in an account that pays
12
%
per year. If the interest earned in the first year is
$
1720
, how much did she invest in each account?

$4,000 in the 10% per year account

$11,000 in the 12% per year account

hello from mrbilldoesmath!

answer:

(7 x + 6 y) (49 x^2 - 42 x y + 36 y^2)

discussion:

the trick is to recognize that 343 = 7^3 and 216 = 6^3 and, in general,

a^3 + b^3 =   (a + b) (a^2 - a b + b^2).

in our case

343x^3+216y^3   =   (7x)^3 + (6y)^3

so take a = 7x and b = 6y in the above equation to get the answer.

you,

mrb

answer: (-6,3)

step-by-step explanation: