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nhiều quá :((
\(a,2\left(x-5\right)-3\left(x+7\right)=14\)
\(2x-10-3x-21=14\)
\(-x-31=14\)
\(-x=45\)
\(x=45\)
\(b,5\left(x-6\right)-2\left(x+3\right)=12\)
\(5x-30-2x-6=12\)
\(3x-36==12\)
\(3x=48\)
\(x=16\)
\(c,3\left(x-4\right)-\left(8-x\right)=12\)
\(3x-12-8+x=0\)
\(4x-20=0\)
\(4x=20\)
\(x=5\)
Cố nốt nha bn !
cảm ơn, bn nha:)))
mà hình như bạn TOP 3 trả lời câu hỏi pải ko nhỉ???
=a, \(\dfrac{x}{15}\) = \(\dfrac{2}{5}\)
= \(x.5=15.2\)
=> \(x=\dfrac{15.2}{5}\)\(=\dfrac{30}{5}\) \(=6\)
Vậy \(x=6\)
b, \(\dfrac{3}{x-7}\) \(=\dfrac{27}{135}\)
= \(\dfrac{3}{x-7}\) \(=\dfrac{3}{15}\)
= \(x-7=15\)
\(x=15+7\)
\(x=22\)
vậy x = 22
c, \(320.x-10=5.48:24\)
= \(320x-10=240:24\)
= \(320x-10=10\)
= \(320x=10+10\)
\(320x=20\)
\(x=20:320\)
\(x=0,0625\)
d, \(5x-1952=\) \(2500-1947\)
\(5x-1952=553\)
\(5x=553+1952\)
\(5x=2505\)
\(x=2505:5\)
\(x=501\)
e, \(\left(x+1\right)+\left(x+2\right)+\left(x+3\right)+\left(x+4\right)\left(x+5\right)=45\)
= \(\left(x+x+x+x+x\right)\)+\(\left(1+2+3+4+5\right)\) \(=45\)
= \(5x+15=45\)
\(5x=45-15\)
\(5x=30\)
\(x=30:5\)
\(x=6\)
f, \(x-\dfrac{2}{3}-\dfrac{2}{15}-\dfrac{2}{35}-\dfrac{2}{63}=\dfrac{1}{9}\)
= \(x-\dfrac{2}{3}-\dfrac{2}{15}-\dfrac{2}{35}=\dfrac{1}{9}+\dfrac{2}{63}\)
= \(x-\dfrac{2}{3}-\dfrac{2}{15}-\dfrac{2}{35}=\dfrac{1}{7}\)
= \(x-\dfrac{2}{3}-\dfrac{2}{15}=\dfrac{1}{7}+\dfrac{2}{35}\)
= \(x-\dfrac{2}{3}-\dfrac{2}{15}=\dfrac{1}{5}\)
= \(x-\dfrac{2}{3}=\dfrac{1}{5}+\dfrac{2}{15}\)
= \(x-\dfrac{2}{3}=\dfrac{1}{3}\)
\(x=\) \(\dfrac{1}{3}+\dfrac{2}{3}\)
\(x=1\)
k, \(\dfrac{3+5+7+...+2015}{2+4+6+...+2014+x}=1\)
ta thấy phần tử là tập hợp các số lẻ ; phần mẫu là tập hợp các số chẵn
mà số chẵn hơn số lẻ 1 đơn vị
nên x thuộc tổng các số phần tử hơn mẫu là 1 đơn vị
=> từ \(2+4+6+...+2014\)có số số hạng là :
( 2014 - 2 ) : 2 + 1 = 1007
vậy x sẽ bằng :
( 1 + 1 ) . 1007 : 2 = 1007
vập số cần tìm là : 1007
1) 2(x + 5) + 3(x + 7) = 41
2x + 10 + 3x + 21 = 41
5x + 31 = 41
5x = 10
x = 2
6) 7(x - 1) + 5(3 - x) = 11x - 10
7x - 7 + 15 - 5x = 11x - 10
2x + 8 = 11x - 10
-9x = -18
x = 2
2) 5(x + 6) + 2(x - 3) = 38
5x + 30 + 2x - 6 = 38
7x + 24 = 38
7x = 14
x = 2
7) 4(2 + x) + 3(x - 2) = 12
8 + 4x + 3x - 6 = 12
7x + 2 = 12
7x = 10
x = 10/7
3) 7(5 + x) + 2(x - 10) = 15
35 + 7x + 2x - 20 = 15
9x + 15 = 15
9x = 0
x = 0
8) 5(2 + x) + 4(3 - x) = 10x - 15
10 + 5x + 12 - 4x = 10x - 15
x + 22 = 10x - 15
9x = 37
x = 37/9
4) 3(x + 4) + (8 - 2x) = 22
3x + 12 + 8 - 2x = 22
x + 20 = 22
x = 2
9) 7(x - 2) + 5(3 - x) = 11x - 6
7x - 14 + 15 - 5x = 11x - 6
2x + 1 = 11x - 6
-9x = -7
x = 7/9
5) 4(x + 5) + 3(7 - x) = 49
4x + 20 + 21 - 3x = 49
x + 41 = 49
x = 8
10) 5(3 - x) + 5(x + 4) = 6 + 4x
15 - 5x + 5x + 20 = 6 + 4x
35 = 6 + 4x
4x = 29
x = 29/4
1. 25 : 5,7 = 250/57
2. 30:2.8.4 = 480
3. 20:2^2.14= 70
4. 125:5^3.170= 170
5. 64:2^5.30.4=240
6. (25:5^2.30): 15.7=14
bạn à! Nhiều quá mình ko làm hết được. sorry nha.^-^
a) \(\left(3^2-2\right).\left(x-12+35\right)\)\(=\)\(5^2+279:5\)
\(7.\left(x-12+35\right)=80,8\)
\(x-12+35=80,8:7\)
\(x-12+35=\frac{404}{35}\)
\(x-12=\frac{404}{35}-35\)
\(x-12=\frac{-821}{35}\)
\(x=\frac{-821}{35}+12\)
\(x=\frac{-401}{35}\)
b) \(260:\left(x+4\right)\)\(=\)\(5\left(2^3+5\right)-3\left(3^2+2^2\right)\)
\(260:\left(x+4\right)=26\)
\(x+4=260:26\)
\(x+4=10\)
\(x=10-4\)
\(x=6\)
c) \(7^{x-3}=343\)
\(7^x:7^3=343\)
\(7^x=343.7^3\)
\(7^x=117649\)
vì \(117649=7^6\Rightarrow x=6\)
d) \(\left(x-3\right)^{2017}=\left(x-3\right)^{2016}\)
\(\Rightarrow\hept{\begin{cases}x-3=1\\x-3=0\end{cases}\Rightarrow\hept{\begin{cases}x=4\\x=3\end{cases}}}\)
e) \(\left(2^3+3\right).\left(x-5\right)+14\)\(=\)\(5^2+124:2^2\)
\(\left(2^3+3\right).\left(x-5\right)+14=56\)
\(\left(2^3+3\right).\left(x-5\right)=56-14\)
\(\left(2^3+3\right).\left(x-5\right)=42\)
\(x-5=42:\left(2^3+3\right)\)
\(x-5=\frac{42}{11}\)
\(x=\frac{42}{11}+5\)
\(x=\frac{97}{11}\)
a) \(12\dfrac{1}{3}-\left(3\dfrac{3}{4}+4\dfrac{3}{4}\right)=\dfrac{37}{3}-\left(\dfrac{15}{4}+\dfrac{19}{4}\right)\)
\(=\dfrac{37}{3}-\dfrac{34}{4}=\dfrac{37}{3}-\dfrac{17}{2}=\dfrac{74}{6}-\dfrac{51}{6}=\dfrac{23}{6}\)
b) \(3\dfrac{5}{6}+2\dfrac{1}{6}.6=\dfrac{23}{6}+\dfrac{13}{6}.6=\dfrac{23}{6}+\dfrac{78}{6}=\dfrac{101}{6}\)
c) \(3\dfrac{1}{2}+4\dfrac{5}{7}-5\dfrac{5}{14}=\dfrac{7}{2}+\dfrac{33}{7}-\dfrac{75}{14}=\dfrac{49}{14}+\dfrac{66}{14}-\dfrac{75}{14}=-\dfrac{92}{14}=-\dfrac{46}{7}\)
d) \(4\dfrac{1}{2}+\dfrac{1}{2}:5\dfrac{1}{2}=\dfrac{9}{2}+\dfrac{1}{2}:\dfrac{11}{2}=\dfrac{9}{2}+\dfrac{1}{2}.\dfrac{2}{11}=\dfrac{9}{2}+\dfrac{1}{11}=\dfrac{99}{22}+\dfrac{2}{22}=\dfrac{101}{22}\)
a. \(12\dfrac{1}{3}-\left(3\dfrac{3}{4}+4\dfrac{3}{4}\right)=\dfrac{37}{3}-\left(\dfrac{15}{4}+\dfrac{19}{4}\right)\)
\(=\dfrac{37}{3}-\dfrac{34}{4}=\dfrac{23}{6}\)
\(b.3\dfrac{5}{6}+2\dfrac{1}{6}.6=\dfrac{23}{6}+13=\dfrac{101}{6}\)
\(c.3\dfrac{1}{2}+4\dfrac{5}{7}-5\dfrac{5}{14}=\dfrac{7}{2}+\dfrac{33}{7}-\dfrac{75}{14}=\dfrac{20}{7}\)
d \(4\dfrac{1}{2}+\dfrac{1}{2}:5\dfrac{1}{2}\)
\(=\dfrac{9}{2}+\dfrac{1}{2}:\dfrac{11}{2}\)
\(=\dfrac{9}{2}+\dfrac{1}{11}\)
\(=\dfrac{101}{22}\)
1/ Suy ra: -35 + 7x - 2x + 20 = 15
5x - 15 = 15
5x = 30
x = 6
2/ Suy ra: 4x - 20 - 3x - 21 = -19
x - 41 = -19
x = 22
3/ Suy ra: 8 - 4x + 3x - 15 = 14
-7 -x = 14
x = -7 -14
x = -21
4/ Suy ra: 7x - 63 - 30 + 5x = -6 + 11x
7x + 5x - 11x = -6 +63 + 30
x = 87
5/ Suy ra: -21x +35 + 14x - 28 = 28
-21x + 14x = 28 +28 - 35
-7x = 21
x= -3
6/ Suy ra: 20 - 5x + 7x - 14 = -2
2x = -8
x = -4
7/ Suy ra: 4x +15 -5x = 7
-x = -8
x = 8
8/ Suy ra: 5x - 35 +30 -10x = 20
-5x - 5 = 20
-5x = 25
x = -5
9/ Suy ra: 35 - 7x + 5x - 10 = 15
-7x + 5x = 15 +10 - 35
-2x = -10
x = 5