Home
Class 12
MATHS
Concept : Let a(0)x^(n)+a(1)x^(n-1)+…+a(...

Concept : Let `a_(0)x^(n)+a_(1)x^(n-1)+…+a_(n-1)x+a_(n)=0` be the nth degree equation with `a_(0),a_(1),…a_(n)` integers. If p/q is a rational root of this equation, then p is a divisor of `a_(n)` and q is a divisor of `a_(0)`. If `a_(0)=1`, then every rational root of this equation must be an integer.
The rational roots of the equation `3x^(3)-x^(2)-3x+1=0` are in

A

A.P.

B

G.P.

C

H.P.

D

none of these

Text Solution

AI Generated Solution

The correct Answer is:
To solve the equation \(3x^3 - x^2 - 3x + 1 = 0\) and find its rational roots, we will follow these steps: ### Step 1: Identify the coefficients The coefficients of the polynomial \(3x^3 - x^2 - 3x + 1\) are: - \(a_0 = 3\) (coefficient of \(x^3\)) - \(a_1 = -1\) (coefficient of \(x^2\)) - \(a_2 = -3\) (coefficient of \(x\)) - \(a_3 = 1\) (constant term) ### Step 2: Apply the Rational Root Theorem According to the Rational Root Theorem, any rational root \(p/q\) of the polynomial must have \(p\) as a divisor of the constant term \(a_3\) and \(q\) as a divisor of the leading coefficient \(a_0\). - Divisors of \(a_3 = 1\): \( \pm 1\) - Divisors of \(a_0 = 3\): \( \pm 1, \pm 3\) ### Step 3: List possible rational roots The possible rational roots (from the combinations of divisors of \(a_3\) and \(a_0\)) are: - \(1\) - \(-1\) - \(\frac{1}{3}\) - \(-\frac{1}{3}\) ### Step 4: Test each possible rational root We will substitute each possible rational root into the polynomial to check if it equals zero. 1. **Testing \(x = 1\)**: \[ 3(1)^3 - (1)^2 - 3(1) + 1 = 3 - 1 - 3 + 1 = 0 \quad \text{(Root found)} \] 2. **Testing \(x = -1\)**: \[ 3(-1)^3 - (-1)^2 - 3(-1) + 1 = -3 - 1 + 3 + 1 = 0 \quad \text{(Root found)} \] 3. **Testing \(x = \frac{1}{3}\)**: \[ 3\left(\frac{1}{3}\right)^3 - \left(\frac{1}{3}\right)^2 - 3\left(\frac{1}{3}\right) + 1 = 3\left(\frac{1}{27}\right) - \left(\frac{1}{9}\right) - 1 + 1 = \frac{1}{9} - \frac{1}{9} - 1 + 1 = 0 \quad \text{(Root found)} \] 4. **Testing \(x = -\frac{1}{3}\)**: \[ 3\left(-\frac{1}{3}\right)^3 - \left(-\frac{1}{3}\right)^2 - 3\left(-\frac{1}{3}\right) + 1 = 3\left(-\frac{1}{27}\right) - \left(\frac{1}{9}\right) + 1 + 1 = -\frac{1}{9} - \frac{1}{9} + 1 + 1 \neq 0 \quad \text{(Not a root)} \] ### Step 5: Conclusion The rational roots of the equation \(3x^3 - x^2 - 3x + 1 = 0\) are: - \(x = 1\) - \(x = -1\) - \(x = \frac{1}{3}\)
Promotional Banner

Similar Questions

Explore conceptually related problems

Let a_0x^n + a_1 x^(n-1) + ... + a_(n-1) x + a_n = 0 be the nth degree equation with a_0, a_1, ... a_n integers. If p/q is arational root of this equation, then p is a divisor of an and q is a divisor of a_n . If a_0 = 1 , then every rationalroot of this equation must be an integer.

Differentiate |x|+a_(0)x^(n)+a_(1)x^(n-1)+a_(2)x^(n-1)+...+a_(n-1)x+a_(n)

If a_(0) = 0.4 and a_(n+1) = 2|a_(n)|-1 , then a_(5) =

If a_(1) = 2 and a_(n) - a_(n-1) = 2n (n ge 2) , find the value of a_(1) + a_(2) + a_(3)+…+a_(20) .

(1+x)^(n)=a_(0)+a_(1)x+a_(2)x^(2) +......+a_(n)x^(n) then Find the sum of the series a_(0) +a_(2)+a_(4) +……

Let a_(0)=0 and a_(n)=3a_(n-1)+1 for n ge 1 . Then the remainder obtained dividing a_(2010) by 11 is

If the equation a_(n)x^(n)+a_(n-1)x^(n-1)+..+a_(1)x=0, a_(1)!=0, n ge2 , has a positive root x=alpha then the equation na_(n)x^(n-1)+(n-1)a_(n-1)x^(n-2)+….+a_(1)=0 has a positive root which is

Let (1 + x^(2))^(2) (1 + x)^(n) = a_(0) + a_(1) x + a_(2) x^(2) + … if a_(1),a_(2) " and " a_(3) are in A.P , the value of n is

If (1+x+x^(2))^(n)=a_(0)+a_(1)x+a_(2)x^(2)+….+a_(2n)x^(2n) , then prove that a_(0)+a_(3)+a_(6)+a_(9)+……=3^(n-1)

Let n in N . If (1+x)^(n)=a_(0)+a_(1)x+a_(2)x^(2)+…….+a_(n)x^(n) and a_(n)-3,a_(n-2), a_(n-1) are in AP, then :