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QJEEM21Ma0b6e: JEE Main 2021 Mathematics - Class 11 JEEM21Ma0b6e Solution: Let 0 be in R. If and are the roots of the equation x 2 x + 2 = …

Let λ\lambda ≠\ne 0 be in R. If α\alpha and β\beta are the roots of the equation x2 −- x + 2 λ\lambda = 0, and α\alpha and γ\gamma are the roots of equation 3x2 −- 10x + 27 λ\lambda = 0, then βγλ{{\beta \gamma } \over \lambda } is equal to ____________.

Step-by-Step Verified Solution

3 α\alpha 2 −- 10 α\alpha + 27 λ\lambda = 0 ..... (1)

α\alpha 2 −- α\alpha + 2 λ\lambda = 0 ...... (2)

(1) −- 3(2) gives

−- 7 α\alpha + 21 λ\lambda = 0 ⇒\Rightarrow α\alpha = 3 λ\lambda

Put α\alpha = 3 λ\lambda in equation (1) we get

9 λ\lambda 2 −- 3 λ\lambda + 2 λ\lambda −- 0

9 λ\lambda 2 = λ\lambda ⇒\Rightarrow λ\lambda = 19{1 \over 9} as λ\lambda ≠\ne 0

Now, α\alpha = 3 λ\lambda ⇒\Rightarrow λ\lambda = 13{1 \over 3}

α\alpha + β\beta = 1 ⇒\Rightarrow β\beta = 2/3

α\alpha + γ\gamma = 103{10 \over 3} ⇒\Rightarrow γ\gamma = 3

βγλ=23×319=18{{\beta \gamma } \over \lambda } = {{{2 \over 3} \times 3} \over {{1 \over 9}}} = 18

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