Let

Bold u left parenthesis t right parenthesisu$($t$)$equals$=7$ t cubed Bold i plus left parenthesis t squared minus $6$ right parenthesis Bold j minus $8$ Bold k$7$t$3$i$+$t$26$j$8$k$.$

Compute the derivative of the following function.

Bold u left parenthesis t Superscript $4$ Baseline minus $2$ t right parenthesisut$42$t

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Part $1$

Select the correct choice below and fill in the answer$$ box$($es$)$ to complete your choice.

A$.$

The derivative is the$$ vector$-$valued function

left parenthesis nothing right parenthesis Bold i plus left parenthesis nothing right parenthesis Bold j plus left parenthesis nothing right parenthesis Bold kenter your response herei$+$enter your response herej$+$enter your response herek.

B$.$

The derivative is the scalar function

enter your response here.