The pair of equation x + 2y + 5 = 0 and - 3x - 6y + 1 = 0 has
Given, equations are x + 2y + 5 = 0 and - 3x - 6y + 1 = 0.
Comparing the equations with general equation of the form:
ax + by + c = 0;
a1x + b1y + c1 = x + 2y + 5
a2x + b2y + c2 = - 3x - 6y + 1
Here, a1 = 1, b1 = 2, c1 = 5
And a2 = - 3, b2 = - 6, c2 = 1
Taking the ratio of coefficients to compare -
a1 /a2 = - 1/3
b1 /b2 = - 1/3
c1 /c2 = 5/1;
here a1/a2 = b1/b2 c1/c2
This represents pair of parallel lines.
Hence, the pair of equations has no solution.
Alternative solution -
We know for a line y = mx +c;
m represents slope of line.
So, we can write this lines in that form first -
For line: x + 2y + 5 = 0
2y = - 5 - x
Hence slope of first line is - 1/2.
For line: - 3x - 6y + 1 = 0
6y = - 3x + 1
Hence slope of second line is - 1/2.
Slope for both the lines represents the lines are parallel and will never intersect and so will have no solution.