1.

Let a differentiable function f:RtoR be such that for all x and y in R 2|f(x)-f(y)|le|x-y| and f^(')(x)ge(1)/(2). So then the number of points of intersection of the graph y=f(x) with

Answer»

the line `y=x` is one.
the curve `y=-x^(3)` is one.
the curve `2y=|x|` is three.
the curve `y^(2)=-x` may be more than one.

Solution :We have `2|f(x)-f(y)|lt|x-y|`
`implies|(f(x)-f(y))/(x-y)|lt(1)/(2)implies|f^(')(x)|lt(1)/(2)`
but `f^(')(x)GE(1)/(2)`. So `f^(')(x)=(1)/(2)` so the curve is`y=(x)/(2)+c`


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