11ya..thanks
If f(x)=sin x + a2x + b is an increasing fn. for all values of x,then --
A. a ε (-∞,-1) U (1,∞)
B. a ε (0,∞)
C. a ε (-1,1)
D. none of these
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2 Answers
11dy/dx =cos x + a2 >0
a2>-cosx
see -1<cosx<1
Therefore 1>-cosx>-1
Therefore a2>1 or a2>-1
a2 cannot be negative therfore
a2>1
a<-1 or a>1
Therefore option A is the ans