Question

question:
x2+(a−b)x+(1−a−b)=0 , a,b∈R. Find the condition on a, for which both roots of the equation are real and unequal.
answer is :
x2+(a−b)x+(1−a−b)=0...(i)
For given condition,
⇒D>0⇒(a−b)2−4(1−a−b)>0
⇒b2−2(a−2)b+(a2+4a−4)>0
⇒(a−2)2−(a2+4a−4)<0⇒−8a+8<0⇒a>1
WHY ARE WE CHECKING D<0 IN SECOND CASE?

Answer 1

Answer:

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