KVPY2014MathematicsQuadratic Equation
Let p(x)=x²-5 x+a and q(x)=x²-3 x+b , where a and b are positive integers. Suppose hof (p(x), q(x)=x-1 and k(x)=1 c m(p(x), q(x)) . If the coefficient of the highest degree term of k(x) is 1, the sum of the roots of (x-1)+k(x) is.
Options
- A4
- B5
- C6
- D7
Correct answer
D. 7
Step-by-step solution
HCF =x-1 p(x)=x²-5 x+a=x²-5 x+4=(x-1)(x-4) ...... (1) and q(x) x²-3 x+b=x²-3 x+2=(x-1)(x-2) k(x)=(x-1)(x-2)(x-4) ...... (2) Hence (x-1)+R(x)=(x-1)+(x-1)(x-2)(x-2)(x-4)=(x-1)(x-3)² Hence sum of roots =7