JEE Advance - Mathematics (2016 - Paper 2 Offline - No. 17)
Let a, $$\lambda$$, m $$\in$$ R. Consider the system of linear equations
ax + 2y = $$\lambda$$
3x $$-$$ 2y = $$\mu$$
Which of the following statements is(are) correct?
Explanation
The given system of linear equation is
ax + 2y = $$\lambda$$
3x $$-$$ 2y = $$\mu$$
By Cramer's rule, we have
$$\Delta = \left| {\matrix{ a & 2 \cr 3 & { - 2} \cr } } \right| = - 2a - 6 = - 2(a + 3)$$
$${\Delta _1} = \left| {\matrix{ \lambda & 2 \cr \mu & { - 2} \cr } } \right| = - 2\lambda - 2\mu = - 2(\lambda + \mu )$$
$${\Delta _2} = \left| {\matrix{ a & \lambda \cr 3 & \mu \cr } } \right| = (a\mu - 3\lambda )$$
For unique solution: $$\Delta$$ $$\ne$$ 0 $$\Rightarrow$$ a + 3 $$\ne$$ 0 $$\Rightarrow$$ a $$\ne$$ $$-$$3, where $$\lambda$$ and $$\mu$$ can take any values.
Hence, option (B) is correct.
For infinite solution: $$\Delta$$ = 0, $$\Delta$$1 and $$\Delta$$2 are zero.
That is, a = $$-$$3 and $$\lambda$$ + $$\mu$$ = 0 or a$$\mu$$ $$-$$ 3$$\lambda$$ = 0.
Hence, options (C) are correct.
For no solution: $$\Delta$$ = 0 and either $$\Delta$$1 or $$\Delta$$2 is non-zero.
That is, a = $$-$$3 and $$\lambda$$ + $$\mu$$ $$\ne$$ 0.
Hence, option (D) is correct.
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