Home
Class 12
MATHS
If f(X) is a polynomial satisfying f(x)f...

If `f(X)` is a polynomial satisfying `f(x)f(1/x)=f(x)+f(1/x)` and `f(2)gt1`, then `lim_(x rarr 1)f(x)` is

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to find the limit \(\lim_{x \to 1} f(x)\) given the polynomial function \(f(x)\) that satisfies the equation: \[ f(x)f\left(\frac{1}{x}\right) = f(x) + f\left(\frac{1}{x}\right) \] and the condition \(f(2) > 1\). ### Step-by-Step Solution: 1. **Understanding the Equation**: We start with the equation: \[ f(x)f\left(\frac{1}{x}\right) = f(x) + f\left(\frac{1}{x}\right) \] This implies a relationship between \(f(x)\) and \(f\left(\frac{1}{x}\right)\). 2. **Rearranging the Equation**: Rearranging gives us: \[ f(x)f\left(\frac{1}{x}\right) - f(x) - f\left(\frac{1}{x}\right) = 0 \] This can be factored as: \[ (f(x) - 1)(f\left(\frac{1}{x}\right) - 1) = 1 \] 3. **Defining a New Function**: Let \(g(x) = f(x) - 1\). Then we can rewrite our equation as: \[ g(x)g\left(\frac{1}{x}\right) = 1 \] This indicates that \(g(x)\) and \(g\left(\frac{1}{x}\right)\) are multiplicative inverses. 4. **Analyzing the Function**: The equation \(g(x)g\left(\frac{1}{x}\right) = 1\) suggests that \(g(x)\) could be of the form \(g(x) = x^n\) for some integer \(n\). This leads to: \[ f(x) = g(x) + 1 = x^n + 1 \] 5. **Using the Condition \(f(2) > 1\)**: We know \(f(2) > 1\): \[ f(2) = 2^n + 1 > 1 \implies 2^n > 0 \] This is true for all integers \(n\). 6. **Finding the Limit**: Now we need to find: \[ \lim_{x \to 1} f(x) = \lim_{x \to 1} (x^n + 1) = 1^n + 1 = 1 + 1 = 2 \] ### Conclusion: Thus, the limit is: \[ \lim_{x \to 1} f(x) = 2 \]
Promotional Banner

Topper's Solved these Questions

  • INVERSE TRIGONOMETRIC FUNCTIONS

    NTA MOCK TESTS|Exercise SINGLE CHOICE |30 Videos
  • JEE MOCK TEST 10

    NTA MOCK TESTS|Exercise MATH|25 Videos

Similar Questions

Explore conceptually related problems

If f(x) is a polynomial satisfying f(x)f((1)/(x))=f(x)+f((1)/(x)) and f(3)=28 then f(4)=

If f(x) is a continuous function satisfying f(x)f(1/x) =f(x)+f(1/x) and f(1) gt 0 then lim_(x to 1) f(x) is equal to

If f(x) is a polynomial function satisfying f(x)*f((1)/(x))=f(x)+f((1)/(x)) and f(4)=65, then find f(6)

If f(x) is a polynomial satisfying f(x)f((1)/(x))=f(x)+f((1)/(x)) and f(3)=28, then f(4) is equal to 63 (b) 65 (c) 17 (d) none of these

If f'(x)=f(x) and f(0)=1 then lim_(x rarr0)(f(x)-1)/(x)=

If f(x) is a polynomial in x(>0) satisfying the equation f(x)+f(1/x)-f(x)f(1/x) and f(2)=-7 , then f(3)=

If f(x) is a polynomial in x satisfying the equation f(x)+f((1)/(x))=f(x)f((1)/(x)) and f(2)=-7 then f(3)=

" If "f(x)" is a polynomial in "x(>0)" satisfying the equation "f(x)+f(1/x)=f(x)f(1/x)" and "f(2)=9" ,then "f(3)" -,"

let f(x) be a polynomial satisfying f(x) : f(1/x) = f(x) + f(1/x) for all XinR :- {O} and f(5) =126, then find f(3).

NTA MOCK TESTS-JEE MOCK TEST 1-MATHEMATICS
  1. What will be the remainder when 5^97 is divided by 52

    Text Solution

    |

  2. If y=4x-5 is a tangent to the curve y^(2)=px^(3) +q at (2, 3), then

    Text Solution

    |

  3. The number of discontinuities of the greatest integer function f(x)=[...

    Text Solution

    |

  4. The number of ways of dividing 15 men and 15 women into 15 couples eac...

    Text Solution

    |

  5. If the general solution of the differential equation y'=y/x+phi(x/y), ...

    Text Solution

    |

  6. If "sin"^(-1)(1)/(3)+"sin"^(-1)(2)/(3)=sin^(-1)x, then the value of x...

    Text Solution

    |

  7. If x!= y, then for every natural number n, x^n - y^n is divisible by

    Text Solution

    |

  8. The area bounded by the curves y=(x-1)^(2),y=(x+1)^(2) " and " y=(1)/(...

    Text Solution

    |

  9. Number of roots of cos^2x+(sqrt(3)+1)/2sinx-(sqrt(3))/4-1=0 which lie ...

    Text Solution

    |

  10. Suppose that the side lengths of a triangles are three consecutive int...

    Text Solution

    |

  11. Let x = 33^n . The index n is given a positive integral value at rando...

    Text Solution

    |

  12. If y=log(10)x+log(x)10+log(x)x+log(10)10 then what is ((dy)/(dx))(x=10...

    Text Solution

    |

  13. If |z|ge3, then determine the least value of |z+(1)/(z)|.

    Text Solution

    |

  14. If a, b, c, d, e, f are in А.Р., then e-c is equal to

    Text Solution

    |

  15. int(log(x+1)-logx)/(x(x+1))dx is equal to :

    Text Solution

    |

  16. If f(X) is a polynomial satisfying f(x)f(1/x)=f(x)+f(1/x) and f(2)gt1,...

    Text Solution

    |

  17. Let A=[[1,0,0], [0, 1, 1], [0,-2, 4]],I=[[1, 0, 0],[ 0 ,1 ,0],[ 0, 0, ...

    Text Solution

    |

  18. The least value of the quadratic polynomial, f(x) = (2p^(2) + 1) x^(2)...

    Text Solution

    |

  19. If A,B,C are in A.P and B=(pi)/4 then tanAtanBtanC=

    Text Solution

    |

  20. Find the distance of the point (-1, 1) from the line 12(x+6)=5(y-2).

    Text Solution

    |