Tìm \(x\) biết:\(\begin{array}{l}a)\;\left( {2x-13...

B

- Hướng dẫn giải

Phương pháp giải:

Sử dụng quy tắc nhân, chia hai lũy thừa cùng cơ số và quy tắc thứ tự thực hiện phép tính để tìm \(x\).

Giải chi tiết:

\(\begin{array}{l}a)\,\,\;\left( {2x-130} \right):4 + 213 = {5^2} + 193\\\,\,\,\,\,\,\left( {2x-130} \right):4 + 213 = 25 + 193\\\,\,\,\,\,\,\left( {2x-130} \right):4 + 213 = 218\\\,\,\,\,\,\,\left( {2x-130} \right):4\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 218 - 213\\\,\,\,\,\,\,\left( {2x-130} \right):4\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 5\\\,\,\,\,\,\,\,2x-130\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 5.4\\\,\,\,\,\,\,\,2x-130\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 20\\\,\,\,\,\,\,\,2x\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 20 + 130\\\,\,\,\,\,\,2x\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 150\\\,\,\,\,\,\,\,\,\,x\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 150:2\\\,\,\,\,\,\,\,\,x\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 75\end{array}\)                                                 

\(\begin{array}{l}b)\,\,\left( {{5^2} + {3^2}} \right)x + \left( {{5^2}-{3^2}} \right)x-50 = {10^2}\\\,\,\,\,\,\,\,\left( {25 + 9} \right)x + \left( {25 - 9} \right)x - 50 = {10^2}\\\,\,\,\,\,\,\,\,34x + 16x - 50\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = {10^2}\\\,\,\,\,\,\,\,\,50x - 50\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 100\\\,\,\,\,\,\,\,\,50x\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 100 + 50\\\,\,\,\,\,\,\,\,50x\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 150\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,x\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 150:50\\\,\,\,\,\,\,\,\,\,\,\,\,\,x\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 3.\\\\\\\\\end{array}\)

Chọn B.