GỌI RA 2021X. B 2021XLN 2021. C 2021X+1. D 2021XLN 2021 .

Câu 26. Gọi R

A

2021

x

.

B

2021

x

ln 2021.

C

2021

x

+

1

.

D

2021

x

ln 2021 .