solve x + y = -2; y = 4x - 7
solve for y and x intercepts
This is a bit unusual. Solving for the intercepts instead of
the point common to both equations.
To solve for intercepts, set one of the variables to 0.
The first equation:
x + y = -2
0 + y = -2
y = -2 The y-intercept
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x + y = -2
x + 0 = -2
x = -2 The x-intercept
The second equation:
y = 4x - 7
y = 4(0) - 7
y = 0 - 7
y = -7 The y-intercept
y = 4x - 7
0 = 4x - 7
-4x = -7
x = 7/4 The x-intercept
However, as long as we are here.....
x + y = -2; y = 4x - 7
Substitute the value of y from the second equation into
the first equation.
x + (4x - 7) = -2
5x -7 = -2
5x = 5
x = 1
x + y = -2
1 + y = -2
y = -3
The point that satisfies both equations is (1, -3),
where the lines intersect.