Question
If a and b are the roots of the equation x2+px+1=0 and ; c and d are the roots of the equation x2+qx+1=0, then (a-c)(b-c)(a+d)(b+d)=?
Answer: Option C
:
C
Shortcut: AssumptionOption (c)Product of roots=1 is the only constraint.Assume values that satisfy the constraint and substitute, take a= -1 and b= -1, then p= 2Assume c= - 1/2 and d= - 2; q= 5/2 Question is = (a-c)(b-c)(a+d)(b+d)=9/4Only option (c) satisfies this => q2 –p2 = 25/4 – 4 =9/4
Was this answer helpful ?
:
C
Shortcut: AssumptionOption (c)Product of roots=1 is the only constraint.Assume values that satisfy the constraint and substitute, take a= -1 and b= -1, then p= 2Assume c= - 1/2 and d= - 2; q= 5/2 Question is = (a-c)(b-c)(a+d)(b+d)=9/4Only option (c) satisfies this => q2 –p2 = 25/4 – 4 =9/4
Was this answer helpful ?
More Questions on This Topic :
Latest Videos
Latest Test Papers
Submit Solution