Tìm số tự nhiên x biết:a, 71.2 – 6.(2x+5) =
10
5
:
10
3
b,
5
x
+
3
4
.
6
8
=
6
9
.
3
4
c, 12:{390:[5.
10
2
– (
5
3
+
x
.
7
2
)]} = 4d,
5
3
.(3x+2):13 =
10
3
:
13
5
:
13
4
...
Đọc tiếp
Tìm số tự nhiên x biết:
a, 71.2 – 6.(2x+5) = 10 5 : 10 3
b, 5 x + 3 4 . 6 8 = 6 9 . 3 4
c, 12:{390:[5. 10 2 – ( 5 3 + x . 7 2 )]} = 4
d, 5 3 .(3x+2):13 = 10 3 : 13 5 : 13 4
a, 71.2 – 6.(2x+5) = 10 5 : 10 3
71.2 – 6.(2x+5) = 10 2
6.(2x+5) = 71.2 – 100
6.(2x+5) = 42
x = 1
b, 5 x + 3 4 . 6 8 = 6 9 . 3 4
5 x + 3 4 . 6 8 = 6 8 . 6 . 3 4
5 x + 3 4 = 6 8 . 6 . 3 4 : 6 8 = 6 . 3 4
5x = 6 . 3 4 - 3 4 = 5 . 3 4
x = 3 4
c, 12:{390:[5. 10 2 – ( 5 3 + x . 7 2 )]} = 4
390:[5. 10 2 – ( 5 3 + x . 7 2 )] = 12:4 = 3
5. 10 2 – ( 5 3 + x . 7 2 ) = 390:3 = 130
5 3 + x . 7 2 = 5. 10 2 – 130 = 370
x . 7 2 = 370 – 5 3 = 245
x = 245: 7 2 = 5
d, 5 3 .(3x+2):13 = 10 3 : 13 5 : 13 4
5 3 .(3x+2):13 = 10 3 : 13
3x+2 = 10 3 : 13 : 5 3 .13 = 8
x = 2