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a
f(x) is positive ∀x∈R
b
f (x) assumes both positive and negative values
c
f (x) =0 has no real roots
d
y = f (x) touches the line y = 0.
answer is A.
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Detailed Solution
We havef(x)=x2−2(sin3−sin2)x−(cos3−cos2)∴ D=4[(sin3−sin2)+(cos3−cos2)] =82sin3−22cosπ4+2+32 As sin3−22>0 and π2<2+32<π∴ D1<0Hence , f(x)>0∀x∈R