What would be the best first step in solving this system?

I'd say the answer would be D) Isolate x in the first equation.

Step-by-step explanation:

1 - I did it in my special calculator, and that's what I got from it.

2 - By isolating the x, you can substitute it into the first problem. For example instead of

x^2 - x + 3y = 5, you'd have

(2y - 1)^2 - (2y - 1) + 3y = 5. With that being said, you'd also have like terms (the y's).

Hope this is what you were looking for :)

ok

step-by-step explanation: