Answer:
Option C
Explanation:
Given , α and β are roots of x2+2x+c=0
∴ Sum of roots , α+β= -coefficient of x / coefficient of x2
⇒ α+β=−21=−2 .......(i)
and products of roots , αβ= costant term/ coefficient of x2
⇒ αβ=c1=c .......(ii)
Since , α2+β2=4 [given]
⇒ (α+β)(α2+β2−αβ)=4
[∵a3+b3=(a+b)(a2+b2−ab)]
⇒ (α+β)[(α2+β2−3αβ)]=4
[∵a2+b2=(a+b)2−2αβ)]
⇒ (−2)[(−2)2−3×c]=4 [ From Eqs,(i) and (ii)]
⇒ (-2)[4-3c]=4
⇒ 4−3c=−42
⇒ 4−3c=−2
⇒ −3c=−2−4
⇒ -3c=-6
c=2