Lindsey is tracking the progress of her plant’s growth. today the plan is 5cm high. the plant grows 1.5 cm per day. what will the height of the plant be after 20 days?

31.5 cm . multiply 20 times 5 then added the 1.5 cm

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

well, because the $0.25 is an added cost depending on how many minutes, the answer would be y = 30 + 0.25x.