Jimmy is planning om adding at least 15 new fish to his pond. He wants to add goldfish, which cost 12$ each, and coy, which cost 18$ each. He does not want to spend more tan 324$ in total. a) Write a system of inequalities and graph.

b) Explain if it is feasible for Jimmy to purchase 10 goldfish and 10 coy.

a. is correct

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