CBSE Class 10 Answered

Find the value of K for which eqaution has real roots

Asked by Divyaa | 25 Mar, 2017, 12:25: PM

Expert Answer

begin mathsize 16px style Since space the space equation space straight x squared minus kx minus 4 equals 0 space is space given space to space have space real space roots comma so comma space its space discriminant equals left parenthesis negative straight k right parenthesis squared minus 4 left parenthesis 1 right parenthesis left parenthesis negative 4 right parenthesis greater than 0 space space..... left parenthesis Using space straight b squared minus 4 ac greater than 0 space for space real space roots space property right parenthesis rightwards double arrow straight k squared plus 16 greater than 0 rightwards double arrow straight k squared greater than negative 16 This space is space not space possible space since space we space have space root space of space straight a space negative space number comma space which space is space not space possible space for space real space numbers. bold So bold space bold dear bold space bold student bold space bold please bold space bold note bold space bold that bold comma bold space bold the bold space bold equation bold space bold in bold space bold the bold space bold question bold space bold should bold space bold be bold space bold x to the power of bold 2 bold minus bold kx bold plus bold 4 bold equals bold 0 bold. so comma space its space discriminant equals left parenthesis negative straight k right parenthesis squared minus 4 left parenthesis 1 right parenthesis left parenthesis 4 right parenthesis greater or equal than 0 space space..... left parenthesis Using space straight b squared minus 4 ac greater or equal than 0 space for space real space and space equal space roots space property right parenthesis rightwards double arrow straight k squared minus 16 greater or equal than 0 rightwards double arrow straight k squared greater or equal than 16 rightwards double arrow straight k greater or equal than plus-or-minus 4 So comma space straight k equals 4 space or space straight k equals negative 4 space for space the space equation space to space have space real space and space equal space roots. end style

Answered by Rebecca Fernandes | 25 Mar, 2017, 05:49: PM

CBSE Class 10 Answered

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CBSE Class 10 Answered

Application Videos

Nature of Roots

Determining roots and nature of roots using discriminan ...

Quadratic Equation Equal Roots

Concept Videos

Concept of discriminant to classify roots of quadratic ...

Nature of Roots

Nature of Roots

Quadratic Equations

D = 0

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