Bài 1 :
( 5x - 2 ) . 7 = 49
5x - 2 = 49 : 7
5x - 2 = 7
5x = 7 + 2
5x =9
x = 9: 5
x = \(\frac{9}{5}\)
Vậy x = \(\frac{9}{5}\).
Bài 2 :
\(2.3^2+4.3^3=2.3^2+2.2.3^2.3=2.3^2.\left(1+2.3\right)\)
\(=18.7\)
\(=126\)
bài tìm x
(5x-2).7=49
=>5x-2=49:7
=>5x-2=7
=>5x=7+2
=>5x=9
=>x=\(\frac{9}{5}\)
bài tính nhanh
2.32+4.33=2.32.(1+2.3)=18.7=126
[5x - 2] . 7 = 49
[5x-2]=49:7=7
5x-2=7
5x=7+2=9
x=9:5
x=9/5 hoặc 1,8