Let p(x)=x2−5x+a and q(x)=x2−3x+b, where a and b are positive integers.Suppose hcf(p(x),q(x)=x−1 and k(x)=lcm(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
A
4
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B
5
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C
6
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D
7
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Solution
The correct option is D 7 ∴HCF=x−1 ⇒p(x)=x2−5x+a x2−5x+4........................(1) (x−1)(x−2) and q(x)x2−3x+b=X2−3x+2 =(x−1)(x−2)......................(2) ⇒k(x)=(x−1)(x−2)(x−4) 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