Evaluate the Integral $$\int 20 x \cos \frac { 1 } { 2 } x d x$$

Multiple Choice

Evaluate the integral.
- $$\int 20 x \cos \frac { 1 } { 2 } x d x$$

A) $80 \sin \left( \frac { 1 } { 2 } \right) x - 40 x \cos \left( \frac { 1 } { 2 } \right) x + C$
B) $20 x \sin \left( \frac { 1 } { 2 } \right) x - 40 \cos \left( \frac { 1 } { 2 } \right) x + C$
C) $40 x \sin \left( \frac { 1 } { 2 } \right) x + 80 \cos \left( \frac { 1 } { 2 } \right) x + C$
D) $20 \sin \left( \frac { 1 } { 2 } \right) x + 40 x \cos \left( \frac { 1 } { 2 } \right) x + C$