Bài toán:Tìm x
2/3 : x/5 + 5/7 = 2/7 : 3/5 + 10/9
Giúp mik nha m.n
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a) Ta có : x.710 = 712
=> x = 72
=> x = 49
b) 520 : x = 515
=> x = 55
=> x = 625
c) 7x + 1 = 50
=> 7x = 49
=> 7x = 72
=> x = 2
d) Sửa 7x + 1 = 23
=> 7x + 1 = 8
=> 7x = 7
=> x = 1
e) (x + 5)2 - 2 = 79
=> (x + 5)2 = 81
=> (x + 5)2 = 92
=> \(\orbr{\begin{cases}x+5=9\\x+5=-9\end{cases}}\Rightarrow\orbr{\begin{cases}x=4\\x=-14\end{cases}}\)
Vậy \(x\in\left\{4;-14\right\}\)
g) (7 - x)3 = 125
=> (7 - x)3 = 53
=> 7 - x = 5
=> x = 2
Vậy x =2
1/ 10(X-7)-8(X+5)=6(-5)+24
10x - 70 - 8x - 40 = -30 +24
2x - 110 = -6
2x = 104
x=52
2/ 8(X-|-7|)-6(X-2)=|-8|.6-50
8(x - 7) - 6(x-2) = 8.6 - 50
8x - 56 - 6x +12 =48 -50
2x - 44 = -2
2x = 42
x=21
3/ 2(4X-8)-7(3+X)=|-4|(3-2)
8x-16 - 21 - 7x = 4.1
x-37=4
x=41
4/ 12(X-4)=6(x-2)-16(X+3)=7|-4|
12x - 48 = 6x - 12 - 16x -48 =7.4
12x - 48 = 28
12x=76
x=19/3
5/ 4(X-5)-7(5-X)+10(5-X)=-3
4x - 20 -35 +7x + 50 -10x = -3
x - 5 = -3
x = -2
Chúc bạn học tốt!
\(=\dfrac{2-1}{1x2}+\dfrac{3-2}{2x3}+\dfrac{4-3}{3x4}+...+\dfrac{10-9}{9x10}=\)
\(=1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+...+\dfrac{1}{9}-\dfrac{1}{10}=\)
\(=1-\dfrac{1}{10}=\dfrac{9}{10}\)
A\(\frac{7}{8}+\frac{7}{12}+\frac{9}{8}+\frac{5}{12}\)
\(=\left(\frac{7}{12}+\frac{5}{12}\right)+\left(\frac{7}{8}+\frac{9}{8}\right)\)
\(=1+2\)
\(=3\)
Dễ mak
nhưng mik nhìn đề thấy dài quá nên ko muốn làm
hihi^_$
(x2-1)2=9
=> x2-1 = 3
x2 = 3+1
x2 = 4
=> x2 = 4 = 22 ( x2=22 )
<=> x = 2
12:{390:[5.102-(53+x.72)]} = 4
390:[5.102-(53+x.72)] = 12:4
390:[5.102-(53+x.72)] = 3
5.102-(53+x.72) = 390 : 3
5.102-(53+x.72) = 130
=> 500-(125+x+49)=130
125+x+49 = 500-130
125+x+49 = 370
125+x = 370-49
125+x = 321
x = 321-125
x = 106
53(3x+2):13=103:(135:134)
53(3x+2):13=103:13
53(3x+2):13= 1000/13
125(3x+2):13 = 1000/13
125(3x+2) = 1000/13 . 13
125(3x+2) = 1000
3x+2 = 1000:125
3x+2 = 8
3x = 8-2
3x = 6
x = 6:3
x = 2
\(\frac{2}{3}:\frac{x}{5}+\frac{5}{7}=\frac{2}{7}:\frac{3}{5}+\frac{10}{9}\)
\(\frac{2}{3}:\frac{x}{5}+\frac{5}{7}=\frac{10}{21}+\frac{10}{9}\)
\(\frac{2}{3}:\frac{x}{5}+\frac{5}{7}=\frac{100}{63}\)
\(\frac{2}{3}:\frac{x}{5}\) \(=\frac{100}{63}-\frac{5}{7}\)
\(\frac{2}{3}:\frac{x}{5}\) \(=\frac{55}{63}\)
\(\frac{x}{5}\) \(=\frac{2}{3}:\frac{55}{63}\)
\(\frac{x}{5}\) \(=\frac{42}{55}\)
\(\frac{x\cdot11}{55}\) \(=\frac{42}{55}\)
\(\Rightarrow x\cdot11=42\)
\(x\) \(=42:11\)
\(x\) \(=\frac{42}{11}\)