The function defined by $$f\left( x \right) = \left( {x + 2} \right){e^{ - x}}$$

Which one of the following curves cut the parabola $${y^2} = 4ax$$ at right angles?

The smallest positive root of the equation, $$\tan x - x = 0$$ lies in

Let $$f$$ and $$g$$ be increasing and decreasing functions, respectively from $$\left[ {0,\infty } \right)$$ to $$\left[ {0,\infty } \right)$$. Let $$h\left( x \right) = f\left( {g\left( x \right)} \right).$$ If $$h\left( 0 \right) = 0,$$ then $$h\left( x \right) - h\left( 1 \right)$$ is