Let f:R→R f : \mathbb{R} \to \mathbb{R} f:R→R be a twice differentiable function such that f(x+y)=f(x)f(y) f(x + y) = f(x) f(y) f(x+y)=f(x)f(y) for all x,y∈R x, y \in \mathbb{R} x,y∈R. If f′(0)=4a f'(0) = 4a f′(0)=4a and f f f satisfies f′′(x)−3af′(x)−f(x)=0 f''(x) - 3a f'(x) - f(x) = 0 f′′(x)−3af′(x)−f(x)=0, where a>0 a > 0 a>0, then the area of the region R = {(x, y) | 0 ≤\leq≤ y ≤\leq≤ f(ax), 0 ≤\leq≤ x ≤\leq≤ 2\ is :