G$($u$)=$ln$2$u$+42$u$-4$

Differentiate the function:

G$*($u$)=-2$u$-42(2$u$+4)$

G$*($u$)=-84$u$2-16$

G$\text{'}($u$)=-64$u$2-16$

G$\text{'}($u$)=2$u$-42$u$+4$