Question

check answer @zepdrix

Answer 1

Looks correct to me.

Answer 2

ok, thx

Answer 3

could you help me with a problem?

Answer 4

Two things:

1) Style Points for not reversing the two items inside the final parentheses.
2) Why do you doubt? You got this!

You could also have written it \(-3y\ln(7)+7^{-3x}\), just to be cute. Or maybe \(-3y\ln(7) + \dfrac{y}{x}\).

No need to be stuck in a can. :-)