Home
Class 11
MATHS
In sub - parts (i) to (x) choose the cor...

In sub - parts (i) to (x) choose the correct option and in sub - parts (xi) to (xv) , answer the questions an instructed.
Given that `alphaandbeta` are the roots equation `x^(2)+x+4` , then the value of `(alpha)/(beta)+(beta)/(alpha)` is

A

`(57)/(4)`

B

`-(57)/(4)`

C

`(49)/(4)`

D

`(75)/(4)`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to find the value of \(\frac{\alpha}{\beta} + \frac{\beta}{\alpha}\) given that \(\alpha\) and \(\beta\) are the roots of the equation \(x^2 + x + 4 = 0\). ### Step-by-Step Solution: 1. **Identify the coefficients**: The given quadratic equation is \(x^2 + x + 4 = 0\). Here, we can identify: - \(a = 1\) - \(b = 1\) - \(c = 4\) 2. **Use Vieta's formulas**: According to Vieta's formulas, for a quadratic equation \(ax^2 + bx + c = 0\): - The sum of the roots \(\alpha + \beta = -\frac{b}{a}\) - The product of the roots \(\alpha \beta = \frac{c}{a}\) Therefore, we calculate: \[ \alpha + \beta = -\frac{1}{1} = -1 \] \[ \alpha \beta = \frac{4}{1} = 4 \] 3. **Express \(\frac{\alpha}{\beta} + \frac{\beta}{\alpha}\)**: We can rewrite \(\frac{\alpha}{\beta} + \frac{\beta}{\alpha}\) as: \[ \frac{\alpha^2 + \beta^2}{\alpha \beta} \] 4. **Calculate \(\alpha^2 + \beta^2\)**: We can use the identity: \[ \alpha^2 + \beta^2 = (\alpha + \beta)^2 - 2\alpha \beta \] Substituting the values we found: \[ \alpha^2 + \beta^2 = (-1)^2 - 2 \cdot 4 = 1 - 8 = -7 \] 5. **Substitute values into the expression**: Now we substitute \(\alpha^2 + \beta^2\) and \(\alpha \beta\) into our expression: \[ \frac{\alpha^2 + \beta^2}{\alpha \beta} = \frac{-7}{4} \] 6. **Final answer**: Thus, the value of \(\frac{\alpha}{\beta} + \frac{\beta}{\alpha}\) is: \[ \boxed{-\frac{7}{4}} \]
Promotional Banner

Topper's Solved these Questions

  • MODEL TEST PAPER - 18

    ICSE|Exercise SECTION - B|10 Videos
  • MODEL TEST PAPER - 18

    ICSE|Exercise SECTION - C|9 Videos
  • MOCK TEST PAPER-2021

    ICSE|Exercise SECTION - C|10 Videos
  • MODEL TEST PAPER - 10

    ICSE|Exercise SECTION - C |5 Videos

Similar Questions

Explore conceptually related problems

In sub - part (i) and (ii) choose the correct option and in sub - part (iii) to (v) answer the questions as instructed. ~qto~p is equivalent to ……

If alpha and beta are roots of the equation x^(2)-2x+1=0 , then the value of (alpha)/(beta)+(beta)/(alpha) is

In sub - part (i) to (x) choose the correct option and in sub - part (xi) to (xy), answer the questions as intructed . Find the value of cosec(-1410^(@)) .

If alpha and beta are the roots of 2x^(2) + 5x - 4 = 0 then find the value of (alpha)/(beta) + (beta)/(alpha) .

In sub - part (i) to (x) choose the correct option and in sub - part (xi) to (xy), answer the questions as intructed . The angle between the lines x-2=0andx+sqrt(3y)-5=0 :

In sub - part (i) to (x) choose the correct option and in sub - part (xi) to (xy), answer the questions as intructed . If A is the A.M between a and b , then (A+2a)/(A-b)+(A+2b)/(A-a)=

In sub - part (i) to (x) choose the correct option and in sub - part (xi) to (xy), answer the questions as intructed . The derivative of 1+x+x^(2)+x(3)+….+x^(50) at x=1:

If alpha and beta are roots of the equation 2x^(2)-3x-5=0 , then the value of (1)/(alpha)+(1)/(beta) is

In sub - part (i) to (x) choose the correct option and in sub - part (xi) to (xy), answer the questions as intructed . If A and B are two sets that n(A-B) =10, n(B-A)=8 and n(AcapB)=3 , them n(AuuB)

In sub - part (i) to (x) choose the correct option and in sub - part (xi) to (xy), answer the questions as intructed . If lim_(xtoa)(x^(9)-a^(9))/(x-a)=lim_(xto5)(4+x) , then a equals :