Answer:
Distributive property
Explanation:
You are distributing the 3 to the parenthesis to get 12x+21 =43
Elimination Method

If we multiply the equation 3 by (-1) we obtain this:

If we add them we obtain 0, therefore there are infinite solutions. So, let's write it in terms of Z
1. Using the 3rd equation we can obtain X(Y,Z)

2. We can replace this value of X in the 1st and 2nd equations

3. If we simplify:

4. We can obtain Y from this two equations:

5. Now, we need to obtain X(Z). We can replace Y in X(Y,Z)

6. If we simplify, we obtain:

7. In conclusion, we obtain that
(X,Y,Z) =
Well, if it is based off the Pythagorean Theorem, here is the formula: a squared plus b squared equals c squared. It also works with c squared minus a squared equals b squared. I hope this helps! Please mark me brainliest!
Answer:
what are your answer choices ? i can still help.
I believe the answer is true.