Nội dung bài giảng
Tìm,số tự nhiên x, biết:
a) \({\rm{}}2.x{\rm{ }}-{\rm{ }}138{\rm{ }} = {2^3}{.3^2}\) b) 231 – ( x – 6 ) = 1339 :13
Giải
a) \({\rm{ }}2.x{\rm{ }}-{\rm{ }}138{\rm{ }} = {2^3}{.3^2}\) \( \Rightarrow \) 2x – 138 = 8 . 9 \( \Rightarrow \) 2x – 138 = 72
\( \Rightarrow \) 2x = 72 +138 \( \Rightarrow \) 2x = 210 \( \Rightarrow \) x = 105
b) 231 – ( x – 6 ) = 1339 :13
\( \Rightarrow \) 231 – ( x – 6) = 103
\( \Rightarrow \) x – 6 = 231 – 103 \( \Rightarrow \) x – 6 = 128
\( \Rightarrow \) x = 128 + 6 \( \Rightarrow \) x = 134