1111111111112222222222222 nhan 7 =
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) (x.7 +8):5=10
x.7 +8= 10.5=50
x.7= 50-8=42
x= 42:7=6
b) 280: (7+3.x)=4
7+3.x= 4.280= 1120
3.x= 1120-7 =1113
x= 1113: 3= 371
c) (x.5) .19:13= 57
(x.5). 19= 57.13= 741
x.5= 741: 19= 39
x= 39:5 =7,8
d) 6.(28-8).x = 72
20.x= 72:6= 12
x= 12: 20= 0,6
e) 4. (36-4.x)= 3,2
36-4.x= 32:4= 0,8
-4.x= 0,8- 36= -35,2
x= -35,2 : -4 = 8,8
f) (x-15).3 :12= 6
(x-15).3 = 6. 12= 72
x-15= 72: 3= 24
x= 24+ 15= 39
g) (x:4+ 6) . 7 = 70
x:4+6= 70:7= 10
x:4= 10-6= 4
x= 4.4 = 16
h) (x:2+50) :5= 12
x:2+ 50= 12.5= 60
x:2= 60-50= 10
x= 10.2=20
l) 5.(7+3.x)= 140
7+3.x= 140:5 = 28
3.x= 28-7 =21
x= 21: 3= 7
k cho mình nhe
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{2}{5}:\frac{3}{7}x\frac{3}{7}:\frac{2}{5}+1999=\)\(\frac{2}{5}x\frac{7}{3}x\frac{3}{7}x\frac{5}{2}+1999=\)\(\left(\frac{2x7x3x5}{5x3x7x2}\right)+1999=\)\(1+1999=2000\)
\(\left(1-\frac{1}{2}\right)x\left(1-\frac{1}{3}\right)x\left(1-\frac{1}{4}\right)x\left(1-\frac{1}{5}\right)\)\(=\left(\frac{2}{2}-\frac{1}{2}\right)\)\(x\left(\frac{3}{3}-\frac{1}{3}\right)\)\(x\left(\frac{4}{4}-\frac{1}{4}\right)\)\(x\left(\frac{5}{5}-\frac{1}{5}\right)\)\(=\frac{1}{2}x\frac{2}{3}x\frac{3}{4}x\frac{4}{5}=\)\(\frac{1x2x3x4}{2x3x4x5}=\frac{1x\left(2x3x4\right)}{\left(2x3x4\right)x5}=\frac{1}{5}\)\(.\)
2/5:3/7 nhân 3/7:2/5+1999
=2/5 nhân 7/3 nhân 3/7nhân 5/2+1999
=14/15 nhân 15/14+1999
=1+1999
=2000
(1-1/2) nhân (1-1/3) nhân (1-1/4) nhân (1-1/5)
=1/2 nhân 2/3 nhân 3/4 nhân 4/5
=24/120
=1/5
![](https://rs.olm.vn/images/avt/0.png?1311)
X x 7 + X x 9 - X - X x 5 = 790
suy ra :
X x ( 9 + 7 ) - X x ( 5 + 1 ) = 790
X x 16 - X x 6 = 790
X x 10 = 790
X = 790 : 10
X = 79
![](https://rs.olm.vn/images/avt/0.png?1311)
7,777777778x10^24
=7,777777778x1024