Discussion
If x + 3y = 5 and 3x + y = 7, then x + y =
*This question is included in Nova Math - Problem Set P: Equations, question #23
| (A) | 1 |
| (B) | ... |
| (C) | ... |
| (D) | ... |
| (E) | ... |
| (F) | ... |
The solution is
Posted: 10/28/2012 20:02
Why were the two added? Because we are looking for x+y?
Thanks
Thanks
Posted: 10/28/2012 22:22
Mona, yes. You kind of have to look for what the question is asking. Since we can scan the units of x and y in each equation and they are (1 and 3) and (3 and 1), we decide if we add the equations, the will add up to 4 and 4, and we can easily divide the resulting equation by 4 to get x + y.
Alternatively we could solve for x and y through substitution or elimination (remember how to solve 2 algebraic equations with 2 unknowns). It will take longer for the purpose of this question.
Alternatively we could solve for x and y through substitution or elimination (remember how to solve 2 algebraic equations with 2 unknowns). It will take longer for the purpose of this question.