Definite Integration Question 428

Question: Let $ f(x)=x^{3}+3x+2 $ and g(x) be the inverse of it. Then the area bounded by g(x), the x-axis, and the ordinate at $ x=-2 $ and $ x=6 $ is

Options:

A) 1/4 sq. units

B) 4/3 sq. units

C) 5/4 sq. units

D) 7/3 sq. units

Show Answer

Answer:

Correct Answer: C

Solution:

[c] The required area will be equal to the area enclosed by $ y=f(x), $ y-axis between the abscissa at $ y=-2 $ and $ y=6 $

Hence, $ A=\int\limits_0^{1}{( 6-f(x) )}dx+\int\limits _{-1}^{0}{( f(x)-(-2) )}dx $

$ =\int\limits_0^{1}{( 4-x^{3}-3x )dx+\int\limits _{-1}^{0}{( x^{3}+3x+4 )}dx=\frac{5}{4}} $ Sq. units.