Question

`int_3^9 x^3/((12 - x)^3 + x^3)` dx = ______ 

Options

• 3

• 6

• 9

• 12

Answer 1

`int_3^9 x^3/((12 - x)^3 + x^3)` dx = 3 

Explanation:

`int_a^b f(x)/(f(x) + f(a + b - x)) dx = 1/2 (b - a)`

∴ `int_3^9 x^3/((12 - x)^3 + x^3) dx = 1/2(9 - 3) = 3`