 okay friends so this is cvac 2018 question and this is the first question of 2018 paper it is of one mark so as I told you this is cvac 2018 okay we are going to solve this so question is if x equals to 3 is one root of the quadratic equation x square minus 2kx minus 6 equals 0 then find the value of k now underlying concept here is concept is you know that if alpha or beta alpha or beta is a root root root of a quadratic equation quadratic equation ax square plus bx plus c equals 0 then then you know that alpha square a alpha square plus b alpha plus c equals 0 or a beta square plus d beta plus c equals 0 that means if you plug in the values of roots in the equation you will get LHS equals to 0 equals to RHS now let us solve this question so what will you write you will write given what is given given is x equals to 3 is a root root of quadratic equation a sorry not a it's x square minus 2kx 2kx minus 6 equals 0 okay so hence therefore you can write therefore 3 square minus 2 into k into 3 minus 6 must be equal to 0 okay that means 9 9 minus 6k minus 6 equals 0 this implies 3 minus 6k equals 0 and hence k is equal to 3 upon 6 which is half okay so hence the solution is k equals to half so we will solve another question in the next session thank you