Verified Solution • 2025–26 Session moderate

QJEEM21Ma1db8: JEE Main 2021 Mathematics - Class 12 JEEM21Ma1db8 Solution: For real numbers and , consider the following system of linear…

For real numbers α\alpha and β\beta , consider the following system of linear equations :

x + y −- z = 2, x + 2y + α\alpha z = 1, 2x −- y + z = β\beta . If the system has infinite solutions, then α\alpha + β\beta is equal to ______________.

Step-by-Step Verified Solution

For infinite solutions

Δ\Delta = Δ\Delta 1 = Δ\Delta 2 = Δ\Delta 3 = 0

Δ\Delta = |11−112α2−11|=0

Δ=|30012α2−11|=0

Δ\Delta = 3(2 + α\alpha ) = 0

⇒\Rightarrow α\alpha = −- 2

Δ2=|12−111−22β1|=0

1(1 + 2 β\beta ) −- 2(1 + 4) −- ( β\beta −- 2) = 0

β\beta −- 7 = 0

β\beta = 7

∴\therefore α\alpha + β\beta = 5

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