The way to think about this (for me, anyway) begins with understanding that 2[something] + 3 = 8x – 1, and our job is to figure out what that something is.
Since this question gives us answer choices, all we really need to do is try each one as the something to see what works. Since they’re not in numerical order, start with A.
2(4x – 2) + 3
8x – 4 + 3
8x – 1
Oooh, look at that! we’re already done! 🙂
(Also, for those worrying along at home, note that 5 answer choices means this isn’t an SAT question. Could be SAT Subject Test, though.)
If you didn’t have answer choices, you’d still start in the same place, but then think through logically. Thought process:
2[something] + 3 = 8x – 1
Hmm..there’s gotta be a 4x in the something otherwise i’ll never get 8x. But if it’s just 4x in there then I’ll end up with 8x + 3, not 8x – 1. How do i take 4 away? By adding a –2 inside the something!
from Tumblr https://ift.tt/2P5dJrR