x=-1 is also a root.. which is also real..
LETA,B,C ε R SUCH THAT 4A+2B+C=0 AND AB>0 THEN EQUATION AX2+BX+C=0 HAS WHICH ROOTS REAL,COMPLEX
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7 Answers
Lokesh Verma
·2008-11-25 08:51:44
4A+2B+C=0
put C= -(4A+2B)
AX2+BX-(4A+2B)=0
A(X2-4) + B(X-2) = 0
A(X-2)(X+2) + B(X-2) = 0
(X-2){ A(X+2) + B } = 0
X=2 is one root
X=-2+B/A is another root..
Lokesh Verma
·2008-11-25 08:53:26
sum of the roots is B/A
since AB is +ve B/A is positive..
so the roots are real!