Where does 2x+y=1 and 9x+3y=-3 intersect?

1 Answer
Nov 27, 2016

By substitution method,

you take one equation and keep a variable on one side and all other variable as well as the independent terms to the other.

2x + y = 1
y = 1 - 2x ......... equation (1)

Now replace this value of y in the other equation,

9x+3y=-3
9x + 3 ( 1 - 2x ) = -3
9x + 3 - 6x = -3
3x = -3-3
So,
x = -2

Now replace this value of x in equation (1) ,
So, y = 1 - 2*(-2)
Therefore,
y = 5

So, the two lines intersect at ( -2, 5 )