JAMIA 2021 — Mathematics PYQ
JAMIA | Mathematics | 2021|f an=αn−βn and α,β are the roots of th equation x2 −6x−2=0,then find the value of 3a9a102a8?
Choose the correct answer:
- A.
2
(Correct Answer) - B.
-2
- C.
3
- D.
-3
2
Explanation
1. Roots α and β satisfy the equation x2−6x−2=0:
α2−6α−2=0⟹α2−2=6α
β2−6β−2=0⟹β2−2=6β
2. Multiply the first equation by α8 and the second by β8:
α10−2α8=6α9
β10−2β8=6β9
3. Subtract the two equations:
(α10−β10)−2(α8−β8)=6(α9−β9)
4. Substitute an=αn−βn:
a10−2a8=6a9
5. Calculate the value of the expression:
3a9a10−2a8=3a96a9
=2
Final Answer:
2
Explanation
1. Roots α and β satisfy the equation x2−6x−2=0:
α2−6α−2=0⟹α2−2=6α
β2−6β−2=0⟹β2−2=6β
2. Multiply the first equation by α8 and the second by β8:
α10−2α8=6α9
β10−2β8=6β9
3. Subtract the two equations:
(α10−β10)−2(α8−β8)=6(α9−β9)
4. Substitute an=αn−βn:
a10−2a8=6a9
5. Calculate the value of the expression:
3a9a10−2a8=3a96a9
=2
Final Answer:
2

