If α, β, where α < β, are the roots of the equation λ x² - (λ + 3)x + 3 = 0 such that (1)/(α) - (1)/(β) = (1)/(3), then the sum of all possible values of λ is:

Solution & Explanation

Related Formula

For a quadratic equation ax² + bx + c = 0: Sum of roots: α + β = -(b)/(a) Product of roots: αβ = (c)/(a)

Core Logic

From the given equation λ x² - (λ + 3)x + 3 = 0:

α + β = (λ + 3)/(λ) αβ = (3)/(λ)

We are given the condition:

(1)/(α) - (1)/(β) = (1)/(3) (β - α)/(αβ) = (1)/(3) β - α = (αβ)/(3) = (3/λ)/(3) = (1)/(λ)
Step 1: Square Identity

We know that (α + β)² - 4αβ = (β - α)². Substitute the known values:

(β - α)² = (1)/(λ²) (α + β)² = ((λ + 3)²)/(λ²)

So, we substitute these into the identity:

((λ + 3)²)/(λ²) - 4((3)/(λ)) = (1)/(λ²)
Step 2: Solving for Lambda

Multiply the entire equation by λ² (assuming λ ≠ 0 because it's a quadratic leading coefficient):

(λ + 3)² - 12λ = 1 λ² + 6λ + 9 - 12λ - 1 = 0 λ² - 6λ + 8 = 0
Step 3: Finding Roots
(λ - 2)(λ - 4) = 0

So, λ = 2 or λ = 4. (The solution notes λ=0 derived from λ³ - 6λ² + 8λ = 0 by cross multiplication, but λ=0 degrades the quadratic. Thus valid λ in 2, 4). Sum of possible values of λ = 2 + 4 = 6.

Chapter Mix

Class 11 Mathematics: Complex Numbers and Quadratic Equations

Reference Study Guides

More Complex Numbers and Quadratic Equations Previous-Year Questions — Page 9

Q26 jee_main_2024_31_jan_morning Properties of Modulus and Argument
If α denotes the number of solutions of |1 - i|^x = 2^x and β = ((|z|)/( (z))), where z = (π)/(4) (1 + i)⁴ ( 1 - √(π) i√(π) + i + √(π) - i1 + √(π) i), i = √(-1), then the distance of the point (α, β) from the line 4x - 3y = 7 is
Numerical Answer. Answer: 3 to 3

Solution

Core Logic
|1 - i|^x = 2^x (√(2))^x = 2^x 2x/2 = 2^x

This implies (x)/(2) = x x = 0. There is exactly 1 solution, so α = 1.

Step 1: Simplify complex number z
(1+i)⁴ = ((1+i)²)² = (1 + i² + 2i)² = (2i)² = -4

Thus, z = -π ( (1-√(π)i)(√(π)-i)π + 1 + (√(π)-i)(1-√(π)i)1 + π )

Step 2: Simplify Bracket

Let's expand the terms directly: z = (π)/(4)(-4) [ √(π) - π i - i - √(π)π + 1 + √(π) - i - π i - √(π)1 + π ]

= -π [ (-i(π+1))/(π+1) + (-i(π+1))/(π+1) ] = -π [ -i - i ] = 2π i
Step 3: Find beta

For z = 2π i: |z| = 2π and (z) = (π)/(2).

β = (|z|)/( (z)) = (2π)/(π/2) = 4
Step 4: Distance from Line

Distance of point (α, β) = (1, 4) from the line 4x - 3y - 7 = 0:

D = |4(1) - 3(4) - 7|√(4² + (-3)²) = (|4 - 12 - 7|)/(5) = (|-15|)/(5) = 3
Chapter Mix

Class 11 Maths: Complex Numbers and Quadratic Equations Class 11 Maths: Straight Lines

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