Cho \(\int {f\left( x \right)dx = F\left( x \right) + C} \). Khi đó \(\int {f\left( {2x - 3} \right)dx} \)

Câu hỏi :

Cho \(\int {f\left( x \right)dx = F\left( x \right) + C} \). Khi đó \(\int {f\left( {2x - 3} \right)dx} \)

A. \(F\left( {2x - 3} \right) + C.\)

B. \(\frac{1}{2}F\left( {2x - 3} \right) + C.\)

C. \(\frac{1}{2}F\left( {2x} \right) - 3 + C.\)

D. \(F\left( {2x} \right) - 3 + C.\)

* Đáp án

B

* Hướng dẫn giải

Đặt \(t = 2x - 3 \Rightarrow dt = 2xdx\).

Khi đó ta có: \(\int {f\left( {2x - 3} \right)dx}  = \frac{1}{2}\int {f\left( t \right)dt} \).

Mà \(\int {f\left( x \right)dx}  = F\left( x \right) + C\) nên \(\int {f\left( t \right)dt}  = F\left( t \right) + C\)\( = F\left( {2x - 3} \right) + C\)

Vậy \(\int {f\left( {2x - 3} \right)dx}  = \frac{1}{2}F\left( {2x - 3} \right) + C\).

Copyright © 2021 HOCTAP247