Q22 / 55 · KVPY 2020 (SA) · Mathematics

Let p1x=x3-2020x2+b1x+c1 and p2x=x3-2021x2+b2x+c2 be polynomials having two common roots α and β. Suppose there exist polynomials q1x and q2x such that p1xq1x+p2xq2x=x2-3x+2. Then the correct identity is

  • Correct answer
    A
    p13+p21+4028=0
  • B
    p13+p21+4026=0
  • C
    p12+p21+4028=0
  • D
    p11+p22+4028=0

Solution

p1xq1x+p2xq2x=x2-3x+2

p1x-p2x=x2+b1-b2x+c1-c2

⇒q1x=1 & q2x=-1

p1x-p2x=x-1x-2

Figure

t+3=2020⇒t=2017

p1x=x-1x-2x-2017

Similarly, p2x=x-1x-2x-2018

(A) p13+p21+4028=0

p13=-4028

p21=0

Hence it is true

Hence, the correct answer is option: 'A'.

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