Lisa invests $4,000 in two types of bonds, bond a and bond b. bond a offers a 10% return, and bond b offers a 6% return. lisa invests $x in bond a and $y in bond b. her total return on the investment is $340. the system of linear equations defining the situation is x+y=4,000 and .1x=.06y=340. the amount lisa invested at the rate of 10% is , and the amount she invested at the rate of 6% is .

Lisa invests $4,000 in two types of bonds, bond A and bond B. A + B = 4000 Bond A offers a 10% return, and bond B offers a 6% return. .10 A + .06 B = 340 Her total return on the investment is $340. since the relationship A+B=4000 must satisfy the setup for all values A and B we can state that A = 2000 + n, and B = 2000 -n afterall: 2000 +n + 2000 - n = 4000 for all n .10(2000+n) + .06(2000-n) = 340, once we know n we know A and B

3/4 and -3/4

or

0.75 and -0.75

but there is no solution for

10 times the smaller number added to 6 times the larger number to get 3 as result.

the absolute values of x and y must be equal and with opposite signs (due to their sum being 0).

therefore, 10 times the negative value can never be compensated by 6 times the same but positive value. the sum will always be negative and not positive (and therefore not +3).

it only works with 10 times the larger (positive) number plus 6 times the smaller (negative) value.

Step-by-step explanation:

x + y = 0

10×x + 6×y = 3

=>

x = -y

10×(-y) + 6×y = 3

-10y + 6y = 3

-4y = 3

y = -3/4

=>

x = -y = -(-3/4) = 3/4

control :

10×(3/4) + 6×(-3/4) = 30/4 - 18/4 = 3

12/4 = 3

3 = 3

correct