why f(x) a quadratic func depoends on sign of " a" in a2+bx+c =0
means like if a>0 f(x) >0 .. nd wen a<0 f(x) <0
i mean why does it npot depend on b,c ??
even after finding out da roots of the EQ am not getting any cnclusion :( plz help
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3 Answers
106if u find the roots ..let one root be m and other n (m>n).. then
f(x) = a(x-m)(x-n)
Now, when x is less than or greater both the roots .. i.e. x<m,n then (x-m)(x-n)
is +ve.. so f(x) sign depends on a whether it is positive or negative .. and its sign is same as that of a
now.. when n<x<m .. then (x-m)(x-n) is -ve... so the sign of f(x) depends on a as well. .. and its sign is opposite to the sign of a as (x-m)(x-n) is -ve
62it is not that the quadratic function does not depend on b and c.
It is only that the value approaches + or - infinity as x approaches infinity depending on wheter a is +ve or -ve
so the orientation of the opening of the quadratic depends on a!
106if a>0 f(x) >0 .. nd wen a<0 f(x) <0
this is not true... f(x) has same sign as that of a when x lies outside the roots in wavy curve method and opposite sign of a when x lies between the roots..
If a>0 then f(x) > 0 if x>m,n or x<m,n and f(x) < 0 if n<x<m .. and vice versa
