Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
các bạn làm theo cách lớp 6 cho minh nha nếu các bạn có câu hỏi mà mình làm đc mình sẽ giúp
a) -12 . (x - 5) + 7 . (3 - x) = 5
=> -12x + 60 + 21 - 7x = 5
=> -12x - 7x = 5 - 60 - 21
=> -19x = -76
=> x = -76 : (-19)
=> x = 4
b) 30 . (x + 2 ) - 6 . (x - 5) - 24 . x = 100
=> 30x + 60 - 6x + 30 - 24x = 100
=> 30x - 6x - 24x = 100 - 30 - 60
=> x . (30 - 6 - 24) = 70 - 60
=> x . 0 = 10 (Vô lí vì ko có số nào . 0 = 10)
=> x thuộc rỗng
\(6\cdot x-5=613\)
\(6\cdot x=613+5\)
\(6\cdot x=618\)
\(x=618\div6\)
\(x=103\)
Vậy \(x=103\)
\(12\cdot x+3\cdot x=30\)
\(x\cdot\left(12+3\right)=30\)
\(x\cdot15=30\)
\(x=30\div15\)
\(x=2\)
Vậy \(x=2\)
\(125-25\cdot\left(x-1\right)=100\)
\(25\cdot\left(x-1\right)=125-100\)
\(25\cdot\left(x-1\right)=25\)
\(x-1=25\div25\)
\(x-1=1\)
\(x=1+1\)
\(x=2\)
Vậy \(x=2\)
\(\left(x-2\right)\cdot\left(x-14\right)=0\)
\(\Rightarrow\) \(x-2=0\) hoặc \(x-14=0\)
TH1: \(x-2=0\) TH2: \(x-14=0\)
\(x=0+2\) \(x=0+14\)
\(x=2\) \(x=14\)
Vậy \(x=2\) hoặc \(x=14\)
\(128-3\cdot\left(x+4\right)=23\)
\(3\cdot\left(x+4\right)=128-23\)
\(3\cdot\left(x+4\right)=105\)
\(x+4=105\div3\)
\(x+4=35\)
\(x=35-4\)
\(x=31\)
Vậy \(x=31\)
12.x+3.x=30
x.(12+3)=30
x.15=30
x =30:15
x =2
125-25.(x-1)=100
25.(x-1)=125-100
25.(x-1)=25
x-1=25:25
x-1=1
x =1+1
x=2
(x-2).(x-14)=0
x=14
128-3.(x+4)=23
3.(x+4)=128-23
3.(x+4)=105
x+4=105:3
x+4=35
x = 35+4
x =39
câu 1 bỏ dấu ngoặc rồi tính
( 36 + 79 ) + ( 145 _ 79 _ 36 )
\(=36+79+145-79-36\)
\(=\left(36-36\right)+\left(79-79\right)+145\)\
\(=0+0+145=145\)
10 _ [ 12 _ ( -9 _ 1 ) ]
\(=10-12-10\)
\(=10-10-12\)
\(=0-12=-12\)
( 38 _ 29 + 43) _ ( 43 + 38 )
\(=38-29+43-43-38\)
\(=\left(38-38\right)+\left(43-43\right)-29\)
\(=0+0-29=-29\)
271 _ [ ( -43 ) + 271 _ ( -17 ) ]
\(=271+43-271-17\)
\(=\left(271-271\right)+\left(43-17\right)\)
\(=0+26=26\)
- 144 _ [ 29 _ ( + 144 ) _ ( + 144 )]
\(=-144-19+144+144\)
\(=\left(-144+144+144\right)-19\)
\(=144-19=125\)
đợi mk lm tiếp câu 2 nha .
bài 2 tính tổng các số nguyên
- 18 < hoặc bằng x < hoặc bằng 17
\(\Rightarrow x\in\left\{-18;-17;-16;....;17\right\}\)
tổng \(x=-18+\left(-17\right)+\left(-16\right)+...+17=-18\)
- 27 < hoặc bằng x < hoặc bằng 27
\(\Rightarrow x\in\left\{-27;-26;-25;..;27\right\}\)
Tổng \(x=-27+\left(-26\right)+\left(-25\right)+...+27=0\)
a) -12.(x - 5) + 7(3 - x) = 5
=> -12x + 60 + 21 - 7x = 5
=> -19x + 81 = 5
=> -19x = 5 - 81
=> -19x = -76
=> x = -76 : (-19)
=> x = 4
b) (x + 1) + (x + 2) + (x + 3) + ... + (x + 20) = 250
=> (x + x + x + ... + x) + (1 + 2 + 3 + ... + 20) = 250
=> 20x + 210 = 250
=> 20x = 250 - 210
=> 20x = 40
= > x = 40 : 20
=> x = 2
\(-12\left(x-5\right)+7\left(3-x\right)=5\)
\(\Leftrightarrow-12x+60+21-7x=5\)
\(\Leftrightarrow-19x+81=5\)
\(\Leftrightarrow81-5=19x\)
\(\Leftrightarrow19x=76\)
\(\Leftrightarrow x=4\)
(-23)+(+31)=8
(-37)+65+(-12)+(-1)=15
tim x
-5<x<5
=> x thuộc {-4;-3;-2;-1;0;1;2;3;4;5}
219-7.(x+1)=10
7.(x+1)=219-10
7.(x+1)=209
x+1=209:7
x+1=27
x =27-1
x =26
(3x-6).3=34
(3x-6).3=81
3x-6 =81:3
3x-6 =27
3x =27+6
3x =33
x =33:3
x =11
a) \(\frac{7}{4}x.\left(\frac{33}{12}+\frac{3333}{2020}+\frac{333333}{303030}+\frac{33333333}{42424242}\right)=32\)
\(\frac{7}{4}x.\left(\frac{33}{12}+\frac{33}{20}+\frac{33}{30}+\frac{33}{42}\right)=32\)
\(\frac{7}{4}x.\left(\frac{33}{3.4}+\frac{33}{4.5}+\frac{33}{5.6}+\frac{33}{6.7}\right)=32\)
\(\frac{7}{4}x.33.\left(\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}\right)=32\)
\(\frac{7}{4}x.33.\left(\frac{1}{3}-\frac{1}{7}\right)=32\)
\(\frac{7}{4}x.33\cdot\frac{4}{21}=32\)
đến đây thì bn tự lm đk r
b) \(\frac{1}{3}+\frac{1}{6}+\frac{1}{10}+\frac{1}{15}+...+\frac{2}{x.\left(x-1\right)}=\frac{2007}{2009}\)
\(\frac{2}{6}+\frac{2}{12}+\frac{2}{20}+\frac{2}{30}+...+\frac{2}{\left(x-1\right).x}=\frac{2007}{2009}\)
\(\frac{2}{2.3}+\frac{2}{3.4}+\frac{2}{4.5}+\frac{2}{5.6}+...+\frac{2}{\left(x-1\right).x}=\frac{2007}{2009}\)
\(2.\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+...+\frac{1}{x-1}-\frac{1}{x}\right)=\frac{2007}{2009}\)
\(2.\left(\frac{1}{2}-\frac{1}{x}\right)=\frac{2007}{2009}\)
\(1-\frac{2}{x}=\frac{2007}{2009}\)
\(\frac{2}{x}=\frac{2}{2009}\)
=> x = 2009
a) 12 : x + 5 = 33
12 : x = 33 - 5
12 : x = 28
x = 12 : 28
x = 1/4
Vậy x = 1/4
b) 5*(x + 19) = 170 - 50
5*(x+19) = 120
x + 19 = 120 : 5
x + 19 = 24
x = 24 - 19
x = 5
Vậy x = 5
c) 11*(x - 6) - 11 = 4*x
11*(x-7) = 4x
11x - 77 = 4x
11x - 4x = 77
7x = 77
x = 11
Vậy x = 11
a. 100 - 7 ( x - 5 ) = 58
<=> 7 ( x - 5 ) = 100 - 58
<=> 7 ( x - 5 ) = 42
<=> x - 5 = 42 : 7
<=> x - 5 = 6
<=> x = 6 + 5
<=> x = 11
Tương tự tiếp.
a;100-7(x-5)=58
=>7(x-5)=100-58=42
=>x-5=42:7=6
=>x=6+5=11
b;12(x-1):3=72
=>12(x-1)=72.3=216
=>x-1=216:12=18
=>x=18+1=19
c;12-4(x-1)=4
=>4(x-1)=12-4=8
=>x-1=8:4=2
=>x=2+1=3
d;32-12x=8
=>12x=32-8=24
=>x=24:12=2
nho h do nhe viet moi tay lam day biet ko