An ordered pair α ,   β for which the system of linear equations 1 + α x + β y + z…

An ordered pair α, β for which the system of linear equations
1+αx+βy+z=2
αx+1+βy+z=3
αx+βy+2z=2 has a unique solution, is :
  1. -3, 1
  2. 1, -3
  3. 2, 4
  4. -4, 2

Solution

For unique solution 1+αβ1α1+β1αβ20

Applying C1C1+C2+C3, we get

α+β+2β1α+β+21+β1α+β+2β20

α+β+21β111+β11β20

α+β+20

Clearly, point 2, 4 satisfying the given condition.

Asked in: JEE Main 2019 (12 Jan Shift 1)

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