Suppose two quadratic equations `a_(1)x^(2)+b_(1)x+c_(1)=0` and `a_(2)x^(2)+b_(2)x+c_(2)=0` have a common root `alpha`, then `a_(1)alpha^(2)+b_(1)alpha+c_(1)=0 " "` …..(1) and `a_(2)alpha^(2)+b_(2)alpha+c_(2)=0 " "` ……(2) Eliminating `alpha` using crose - multiplication method gives us the condition for a common root Solving two equations simultaneously, the common root can be obtained. Now, consider three quadratic equations, `x^(2)-2r p_(r )x+r=0, r=1, 2, 3` given that each pair has exactly one root common. In the notations of above problem, `(gamma)/(alpha)` is equal to
A
2
B
3
C
`1//2`
D
`1//3`
Text Solution
AI Generated Solution
The correct Answer is:
To solve the problem step by step, we will first analyze the given quadratic equations and then derive the required relationship between the roots.
### Step 1: Write the Quadratic Equations
We have three quadratic equations given as:
1. \( x^2 - 2p_1x + 1 = 0 \) (for \( r = 1 \))
2. \( x^2 - 4p_2x + 2 = 0 \) (for \( r = 2 \))
3. \( x^2 - 6p_3x + 3 = 0 \) (for \( r = 3 \))
### Step 2: Identify Common Roots
We know that each pair of equations has exactly one root in common. Let’s denote the common roots as follows:
- Let \( \beta \) be the common root of the first two equations.
- Let \( \gamma \) be the common root of the second and third equations.
- Let \( \alpha \) be the common root of the first and third equations.
### Step 3: Use Vieta's Formulas
From Vieta's formulas, we can express the relationships between the roots and coefficients of the quadratic equations:
- For the first equation: \( \beta + \alpha = 2p_1 \) and \( \beta \alpha = 1 \)
- For the second equation: \( \beta + \gamma = 4p_2 \) and \( \beta \gamma = 2 \)
- For the third equation: \( \gamma + \alpha = 6p_3 \) and \( \gamma \alpha = 3 \)
### Step 4: Express Roots in Terms of Each Other
From the product of the roots:
1. From \( \beta \alpha = 1 \), we can express \( \alpha = \frac{1}{\beta} \).
2. From \( \beta \gamma = 2 \), we can express \( \gamma = \frac{2}{\beta} \).
3. From \( \gamma \alpha = 3 \), substituting \( \alpha \) gives \( \gamma \cdot \frac{1}{\beta} = 3 \) or \( \gamma = 3\beta \).
### Step 5: Set Up Equations
Now we have:
- \( \gamma = \frac{2}{\beta} \) and \( \gamma = 3\beta \).
Equating these two expressions for \( \gamma \):
\[
\frac{2}{\beta} = 3\beta
\]
### Step 6: Solve for \( \beta \)
Multiply both sides by \( \beta \):
\[
2 = 3\beta^2
\]
\[
\beta^2 = \frac{2}{3}
\]
\[
\beta = \pm \sqrt{\frac{2}{3}} = \pm \frac{\sqrt{6}}{3}
\]
### Step 7: Find \( \alpha \) and \( \gamma \)
Using \( \beta \):
1. \( \alpha = \frac{1}{\beta} = \pm \frac{3}{\sqrt{6}} = \pm \frac{\sqrt{6}}{2} \).
2. \( \gamma = 3\beta = \pm 3 \cdot \frac{\sqrt{6}}{3} = \pm \sqrt{6} \).
### Step 8: Find \( \frac{\gamma}{\alpha} \)
Now we can find the ratio:
\[
\frac{\gamma}{\alpha} = \frac{\pm \sqrt{6}}{\pm \frac{\sqrt{6}}{2}} = 2
\]
### Conclusion
Thus, the value of \( \frac{\gamma}{\alpha} \) is \( 2 \).
Topper's Solved these Questions
QUADRATIC EQUATION & EXPRESSION
FIITJEE|Exercise NUMERICAL BASED|3 Videos
QUADRATIC EQUATION & EXPRESSION
FIITJEE|Exercise COMPREHENSIONS - II|3 Videos
PROGRESSION & SERIES
FIITJEE|Exercise NUMERICAL BASED|3 Videos
SET, RELATION & FUNCTION
FIITJEE|Exercise Exercise 3|8 Videos
Similar Questions
Explore conceptually related problems
If a_(1)x^(2)+b_(1)x+c_(1)=0 and a_(2)x^(2)+b_(2)x+c_(2)=0 has a common root,then the common root is
If two equation a_(1) x^(2) + b_(1) x + c_(1) = 0 and, a_(2) x^(2) + b_(2) x + c_(2) = 0 have a common root, then the value of (a_(1) b_(2) - a_(2) b_(1)) (b_(1) c_(2) - b_(2) c_(1)) , is
For two linear equations a_(1)x + b_(1)y + c_(1)= 0 and a_(2) x+ b_(2)y+ c_(2)= 0 , then condition (a_(1))/(a_(2)) = (b_(1))/(b_(2))= (c_(1))/(c_(2)) is for
Find the common factors of the expressions a_(1)x^(2)+b_(1)x+c_(1)anda_(2)x^(2)+b_(2)x+c_(1) where c_(1)ne0 .
If the lines a_(1)x+b_(1)y+c_(1)=0 and a_(2)x+b_(2)y+c_(2)=0 cut the coordinae axes at concyclic points,then prove that |a_(1)a_(2)|=|b_(1)b_(2)|
If (a_(1)x^(2)+b_(x)+c_(1))y+(a_(2)x^(2)+b_(2)x+c_(1))=0 find condition that x is a rational function of y.
If the roots of a_(1)x^(2)+b_(1)x+c_(1)=0 are alpha_(1),beta_(1) and those of a_(2)x^(2)+b_(2)x+c_(2)=0 are alpha_(2),beta_(2) such that alpha_(1)alpha_(2)=beta_(1)beta_(2)=1 then
FIITJEE-QUADRATIC EQUATION & EXPRESSION -COMPREHENSIONS - III