Condition for infinite number of solutions (coincident lines) :-
=》a₁/a₂ = b₁/b₂ = c₁/c₂
Equations :-
1) y = -3x + 6
=》y + 3x - 6 = 0
2) By - 9x + 18 = 0
Here,
a₁ = 1, a₂ = B
b₁ = 3, b₂ = -9
c₁ = -6, c₂ = 18
Now substitute..
a₁/a₂ = b₁/b₂ = c₁/c₂
=》1/B = 3/-9 = -6/18
=》1/B = -3/9 = -6/18
Now,
=》a₁/a₂ = b₁/b₂
=》1/B = -3/9 (cross multiplication)
=》1 × 9 = -3B
=》9 = -3B
=》9/-3 = B
=》-3 = B
OR
=》a₁/a₂ = c₁/c₂
=》1/B = -6/18 (cross multiplication)
=》1 × 18 = -6B
=》 18 = -6B
=》18/-6 = B
=》-3 = B
The value of B if the following linear system has an infinite number of solutions is -3.
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