JEE Advance - Mathematics (1982 - No. 9)
The area bounded by the curves $$y=f(x)$$, the $$x$$-axis and the ordinates $$x=1$$ and $$x=b$$ is $$(b-1)$$ sin $$(3b+4)$$. Then $$f(x)$$ is
$$\left( {x - 1} \right)\cos \left( {3x + 4} \right)$$
$$\sin \left( {3x + 4} \right)$$
$$\sin \left( {3x + 4} \right) + 3\left( {x - 1} \right)\cos \left( {3x + 4} \right)$$
none of these