Let three quadratic equations ax2−2bx+c=0,bx2−2cx+a=0 and cx2−2ax+b=0, all have only positive roots. Then which of these are always true?
see full answer
Your Exam Success, Personally Taken Care Of
1:1 expert mentors customize learning to your strength and weaknesses – so you score higher in school , IIT JEE and NEET entrance exams.
An Intiative by Sri Chaitanya
a
b2 = ac
b
c2 = ab
c
each pair of equations has exactly one root common
d
each pair of equations has two roots common
answer is A.
(Unlock A.I Detailed Solution for FREE)
Best Courses for You
JEE
NEET
Foundation JEE
Foundation NEET
CBSE
Detailed Solution
For each equation, required conditions(i) Discriminant≥0⇒b2≥ac,c2≥ab,a2≥bc(ii) f(0)>0 ⇒c,a,b>0(iii) Abscissa of vertex > 0 ⇒ba>0,cb>0,ac>0.Now, b2≥ac,c2≥ab⇒b2c2≥a2bc⇒bc≥a2But a2≥bc. So, a2=bc.Similarly, b2 = ac and c2 = ab.Therefore, a = b = c.