Re: What is the value of y in the system above?
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03 Apr 2013, 05:42
is there an easier and quicker way to solve this question than my approach? this one took me around 6 minutes to solve, so i guess there must be an easier way.
my approach:
1. from the given system of equations i can make equation II. to be x + y = z
2. now put that in III. :
2x + 2y - (x + y) = 1
= 2x + 2y - x - y = 1
= x + y = 1
that gives us z = 1!
3. put z = 1 in I. and solve:
x + 2y + 3 = 2; calculate minus 3
= x + 2y = -1; calculate minus x
= 2y = -1 - x;
4. now put 2y = -1 - x in III. and solve:
2x + (-1 - x) - 1 = 1
= x - 2 = 1; calculate plus 2
that gives us x = 3
5. now solve for y with x = 3 and z = 1:
x + y = 1
= 3 + y = 1; calculate minus 3
that gives y = -2, and hence answer (A) -2
any quicker way?