Do the following equations represent a pair of coincident lines? Justify your answer.
(i) and 7x + 3y = 7
(ii) - 2x - 3y = 1 and 6y + 4x = - 2
(iii)
Condition for coincident lines,
a1/a2 = b1/b2 = c1/c2;
(i) No.
Given pair of linear equations
and 7x + 3y = 7
Comparing with ax + by + c = 0;
Here, a1 = 3, b1 = 1/7, c1 = - 3;
And a2 = 7, b2 = 3, c2 = - 7;
a1 /a2 = 3/7
b1 /b2 = 1/21
c1 /c2 = - 3/ - 7 = 3/7
Here, a1/a2 b1/b2.
Hence, the given pair of linear equations has unique solution.
(ii) Yes, given pair of linear equations.
- 2x - 3y - 1 = 0 and 4x + 6y + 2 = 0;
Comparing with ax + by + c = 0;
Here, a1 = - 2, b1 = - 3, c1 = - 1;
And a2 = 4, b2 = 6, c2 = 2;
a1 /a2 = - 2/4 = - 1/2
b1 /b2 = - 3/6 = - 1/2
c1 /c2 = - 1/2
Here, a1/a2 = b1/b2 = c1/c2, i.e. coincident lines
Hence, the given pair of linear equations is coincident.
(ii) No, given pair of linear equations are
and = 0
Comparing with ax + by + c = 0;
Here, a1 = 1/2, b1 = 1, c1 = 2/5;
And a2 = 4, b2 = 8, c2 = 5/16;
a1 /a2 = 1/8
b1 /b2 = 1/8
c1 /c2 = 32/25
Here, a1/a2 = b1/b2 c1/c2, i.e. parallel lines
Hence, the given pair of linear equations has no solution.