Answer:
y = -1
Step-by-step explanation:
The standard form of equation of a line is y = mx+b
m is the slope
b is the y intercept
Get the coordinate of the point of interception of the line 2x - y = 9 and 3x - 7y = 19
Make y the subject of the formula in both expressions
For 2x - y = 9
- y = 9- 2x
y = 2x - 9
Similarly for 3x - 7y = 19
-7y = 19 - 3x
7y = 3x - 19
y = 3/7 x - 19/7
Equating both expressions
2x - 9 = 3/7 x - 19/7
Multiply through ny 7
14x - 63 = 3x - 19
14x - 3x = -19 + 63
11x = 44
x = 44/11
x = 4
Since y =2x - 9
y = 2(4) - 9
y = 8-9
y = -1
Hence the coordinate of intersection is at (4, -1)
Get the equation of the line passing through (-3, -1) and (4, -1)
Slope m = -1+1/4+3
m = 0/7
m = 0
Get the intercept
Substitute m = 0 and (-3, -1) into y = mx+b
-1 = 0(-3) + b
-1 = b
b = -1
Get the required equation
Recall that y = mx + b
y = 0x + (-1)
y = -1
Hence the required equation is y = -1
