Question

Which is the solution of the system
x + y = -2
2x - 3y = -9

A. (-4,2)
B. (-3,1)
C. (-3,-5)
D. (4,-6)

Answer 1

What method are you used to using, in solving systems?

Answer 2

I dunno

Answer 3

Let's stick with the basic substitution method then.
Let's look at the equation
x + y = -2
Could you solve for y here?
By solve for y, I mean, express y in terms of x.

Or, in other words, bring all terms without y to the right side...

Answer 4

I'm still confused.

Answer 5

Well then,
x + y = -2
What happens when you subtract x from both sides?

Answer 6

I don't know. I'm retarded with this stuff.

Answer 7

x + y = -2
subtract x from both sides:
x - x + y = -2 - x
y = -2 - x
the x has disappeared on left hand side and we have y in terms of x

do you follow that?

Answer 8

the idea is to get y on its own on one side of the '='
and we achieved this by getting rid of the x on lefthand side.
an equation is like a chemical balance
whatever you do to one side you have to do to the other to maintain the balance
we subtracted x from LHS so we had to subtract from RHS

Answer 9

hey the easy method which saves time when we donno the process is direct substitution this may help some times the correct ans is option B.(-3,1)