![](https://rs.olm.vn/images/avt/0.png?1311)
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, 100 - 7 x ( x - 5 ) = 58
7 x ( x - 5 ) = 100 - 58
7 x ( x - 5 ) = 42
( x - 5 ) = 42 : 7
x - 5 = 6
x = 6 + 5
x = 11
b, 24 + 5 * x = 49
5 * x = 49 - 24
5 * x = 25
x = 25 : 5
x = 5
c, x - 105 : 21 = 15
x - 5 = 15
x = 15 + 5
x = 20
d, ( x - 105 ) : 21 = 15
( x - 105 ) = 15 x 21
x - 105 = 315
x = 315 + 105
x = 420
![](https://rs.olm.vn/images/avt/0.png?1311)
1) \(2^x-15=17\)
\(\Leftrightarrow2^x=32=2^5\)
\(\Rightarrow x=5\)
2) \(\left(7x-11\right)^3=25\cdot5^2+200\)
\(\Leftrightarrow\left(7x-11\right)^3=825\)
\(\Leftrightarrow7x-11=\sqrt[3]{825}\)
\(\Leftrightarrow7x=11+\sqrt[3]{825}\)
\(\Rightarrow x=\frac{11+\sqrt[3]{825}}{7}\)
3) \(\left(x+1\right)^{100}-3\left(x+1\right)^{99}=0\)
\(\Leftrightarrow\left(x+1\right)^{99}\left(x-2\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}\left(x+1\right)^{99}=0\\x-2=0\end{cases}}\Rightarrow\orbr{\begin{cases}x=-1\\x=2\end{cases}}\)
4) \(4x+5\left(x+3\right)=105\)
\(\Leftrightarrow9x+15=105\)
\(\Leftrightarrow9x=90\)
\(\Rightarrow x=10\)
5) \(5\cdot\left(x-2\right)+10\left(x+3\right)=170\)
\(\Leftrightarrow5\left[x-2+2\left(x+3\right)\right]=170\)
\(\Leftrightarrow3x+4=34\)
\(\Leftrightarrow3x=30\)
\(\Rightarrow x=10\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Tính nhanh:
9 x 8 x 5 + 15 x 3 x 71 + 45
= 45 x 8 + 45 x 71 + 45
= 45 x ( 8 + 71 + 1 )
= 45 x 80
= 3600
Tính tổng:
A = 115 + 110 + 105 + ... + 20 + 15
A= ( 15 + 115 ) x [ ( 115 - 15 ) : 5 + 1 ]
A = 130 x 21
A = 2730
B = 99 - 97 + 95 - 93 + ... + 51 - 49
B = ( 99 - 97 ) + ( 95 -93 ) +...+ ( 51 - 49 )
B = 2 + 2 +...+ 2
B = 2 x 26
B = 52
C= 31 + 34 + 37 +...+ 91
C= ( 91 + 31 ) x [ ( 91 - 31 ) : 3 + 1 ]
C= 122 x 21
C= 2562
![](https://rs.olm.vn/images/avt/0.png?1311)
\(x-\frac{20}{11.13}-\frac{20}{13.15}-\frac{20}{15.17}-...-\frac{20}{53.55}=\frac{3}{11}\)
Đặt \(A=\frac{20}{11.13}-\frac{20}{13.15}-\frac{20}{15.17}-...+\frac{20}{53.55}\)
\(A=\frac{10.2}{11.13}-\frac{10.2}{13.15}-\frac{10.2}{15.17}-...-\frac{10.2}{53.55}\)
\(A=10\left(\frac{2}{11.13}-\frac{2}{13.15}-\frac{2}{15.17}-...-\frac{2}{53.55}\right)\)
\(A=10\left(\frac{1}{11}-\frac{1}{55}\right)\)
\(A=10.\frac{4}{55}\)
\(A=\frac{40}{55}\)\(A=10.\left(\frac{1}{11}-\frac{1}{13}+\frac{1}{13}-\frac{1}{15}+\frac{1}{15}-\frac{1}{17}+...+\frac{1}{53}-\frac{1}{55}\right)\)
![](https://rs.olm.vn/images/avt/0.png?1311)
x-140 : 35 = 270
x-140 = 270 . 35
x-140 = 9450
x = 9450+140
x = 9590
Vậy x = 9590
(2010-x : 24) + 57= 100
(2010-x : 24) = 100 - 57
(2010-x : 24) = 43
2010-X = 43.24
2010-X =1032
x = 2010-1032
x = 978
Vậy x = 978
1482- 34 . x = 444
34 . x = 1482 - 444
34 . x = 1038
x = 1038 :34
x = 519/17
Vậy x = 519/17
15.x+ 15.2,7 = 105
15.x+15. 27/10=105
15.(x+27/10) = 105
x+27/10= 105: 15
x+27/10= 7
x= 7- 27/10
x= 43/10
Vậy x= 43/10
Đây là phương án riêng của mik, bn nhớ k cho mik nha!!!!!! Mak chỉ là tính toán thường thôi mak, thà sai còn hơn là copy bài của người khác. Ko phải mik giáo huấn, dạy dỗ ai cả, mik chỉ đưa ra ý kiến riêng của mik thui, ko mún ăn gạch đá ^_^!!!!!!!!!!! THANKS BN NHIỀU!!!!!!!!~~~~~~~~~~~~~~~~~~
a)x-140:35=270
=>x-4=270
=>x=270+4
=>x=274
Vậy x = 274.
b)(2010-x:24)+57=100
=>2010-x:24=100-57
=>2010-x:24=43
=>x:24=2010-43
=>x:24=1967
=>x=1967.24
=>x=47208
Vậy x=47208.
c)1482-34.x=444
=>34.x=1482-444
=>34.x=1083
=>x=1083:34
=>x=1083/34.
Vậy x=1083/34.
d)15.x+15.2,7=105
=>15.(x+2,7)=105
=>x+2,7=105:15
=>x+2,7=7
=>x=7-2,7
=>x=4,3.
Vậy x=4,3
![](https://rs.olm.vn/images/avt/0.png?1311)
29 . ( 85 -47) + 85. ( 47-29 )
=29.38+85.18
=1102+1530
=1632
2,7 . 10,5 - 7,3 . 10,5 - 7,3 . 15 + 2,7 . 15
=(2,7+7,3).10,5-(2,7+7,3).15
=10.10,5-10.15
=105-150
=-45
![](https://rs.olm.vn/images/avt/0.png?1311)
1,6 + (2,7 - 0,7.6) - (94.0,7 - 99. 2,7)
= 1,6 + (2,7 - 4,2) - (94.0,7 - 99.2,7)
= 1,6 + -1,5 - (65,8 - 267,3)
= 0,1 - (-201,5)
= 201,6
![](https://rs.olm.vn/images/avt/0.png?1311)
a) \(\left(x-15\right)-75=0\\ \Leftrightarrow x-15=75\\ \Leftrightarrow x=90\)
b) \(575-\left(6x+70\right)=445\\ \Leftrightarrow6x+70=130\\ \Leftrightarrow6x=60\\ \Leftrightarrow x=10\)
c) \(x-105:21=15\\ \Leftrightarrow x-5=15\\ \Leftrightarrow x=20\)
d) \(\left(x-105\right):21=15\\ \Leftrightarrow x-105=315\\ \Leftrightarrow x=420\)
a) ( x - 15 ) - 75 = 0
x -15 = 75 + 0
x - 15 = 75
x= 75 + 15
x = 90
b) 575- (6x +70) =445
6x + 70 = 575 - 545
6x + 70 = 130
6x = 130 - 70
6x = 60
x = 60 : 6
x = 10
c) x –105 : 21 =15
x –105 = 15 x 21
x -105 = 315
x = 315 + 105
x = 420
d) (x - 105) :21 = 15
x - 105 = 21
x = 105 + 21
x = 126
![](https://rs.olm.vn/images/avt/0.png?1311)
15.x + 15.2,7 =105
15.x + 40,5 = 105
15.x = 105 - 40,5
15.x = 64,5
x = 64,5 : 15
x = 4,3
\(15\cdot x+15\cdot2,7=105\)
\(15\cdot x+40,5=105\)
\(15\cdot x=105-40,5\)
\(15\cdot x=64,5\)
\(x=64,5:15\)
\(x=4,3\)