Tìm x biết:
a, ( x – 266) : 5 = 7
b, (x - 129) × 4 = 36
c, 786 – x = 5 × 4 : 2
d, x + 24 : 4 × 3 = 285
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\(a)x=\dfrac{1}{4}+\dfrac{5}{13}=\dfrac{33}{52}.\\ b)\dfrac{x}{3}=\dfrac{2}{3}+\dfrac{-1}{7}.\\ \Leftrightarrow\dfrac{x}{3}=\dfrac{11}{21}.\\ \Leftrightarrow\dfrac{7x}{21}=\dfrac{11}{21}.\\ \Rightarrow7x=11.\\ \Leftrightarrow x=\dfrac{11}{7}.\\ c)\dfrac{x}{3}=\dfrac{16}{24}+\dfrac{24}{36}=\dfrac{2}{3}+\dfrac{2}{3}=\dfrac{4}{3}.\\ \Rightarrow x=4.\\ d)\dfrac{x}{15}=\dfrac{1}{5}+\dfrac{2}{3}=\dfrac{13}{15}.\\ \Rightarrow x=13.\)
\(a,2.\left(x-5\right)-3.\left(x+7\right)=14\)
\(2x-10-3x-21=14\)
\(-x-31=14\)
\(x=-31-14\)
\(x=-45\)
\(b,5.\left(x-6\right)-2\left(x+3\right)=12\)
\(5x-30-2x-6=12\)
\(3x-36=12\)
\(3x=12+36\)
\(3x=48\)
\(x=16\)
\(c,-5.\left(2-x\right)+4.\left(x-3\right)=10.x-15\)
\(-10+5x+4x-12=10x-15\)
\(-6x-22=10x-15\)
\(-6x-10x=-15+22\)
\(-16x=7\)
\(x=-\frac{7}{16}\)
Câu d , e f tương tự nha
\(a)3-\left(17-x\right)=-24+12\)
\(\Leftrightarrow3-17+x=-12\)
\(\Leftrightarrow-14+x=-12\)
\(\Leftrightarrow x=-12+14=2\)
a) 3 - (17 - x) = -24 + 12
=> 3 - 17 + x = -12
=> -14 + x = -12
=> x = -12 + 14
=> x = 2
b) -5 + (16 - x) = 22.3 - 52
=> -5 + 16 - x = 12 - 25
=> 11 - x = -13
=> x = 11 + 13
=> x = 24
c) -26 - (x - 7) = 34 - 92
=> -26 - x + 7 = 81 - 81
=> -19 - x = 0
=> x = -19 - 0
=> x = -19
d) -36 - (4 - x) = 37 + (-5)
=> -36 - 4 + x = 32
=> -40 + x = 32
=> x = 32 + 40
=> x = 72
a: \(\Leftrightarrow x\in\left\{1;-1;2;-2;3;-3;4;-4;6;-6;9;-9;12;-12;18;-18;36;-36\right\}\)
mà -3<x<30
nên \(x\in\left\{-2;-1;1;2;3;4;6;9;12;18\right\}\)
b: \(\Leftrightarrow x\in\left\{0;4;-4;8;-8;12;-12;...\right\}\)
mà -16<=x<20
nên \(x\in\left\{-16;-12;-8;-4;0;4;8;12;16\right\}\)
c: \(\Leftrightarrow x-1+4⋮x-1\)
\(\Leftrightarrow x-1\in\left\{1;-1;2;-2;4;-4\right\}\)
hay \(x\in\left\{2;0;3;-1;5;-3\right\}\)
d: \(\Leftrightarrow2x+4-5⋮x+2\)
\(\Leftrightarrow x+2\in\left\{1;-1;5;-5\right\}\)
hay \(x\in\left\{-1;-3;3;-7\right\}\)
a. 37-7.(x+1)=40-8.3
37 - 7(x+1) = 16
7(x+1) = 21
x+1 = 3
x=2
b. (x+5).3=11=10+(3+4).4
(sao có 2 dấu bằng, dấu nào là dấu cộng do viết nhầm ???)
c. 25-5.3+4.10=100-5.x
50 = 100 - 5x
5x = 50
x=10
d. 36+2.(x-7)=12+8.(3+5)-36
36 + 2(x-7) = 40
2(x-7) = 4
x-7 =2
x=9
e. 3.(x+7)-9=11.5-5-8
3(x+7) - 9 = 42
3(x+7) = 51
x+7 = 17
x=10
a) ( x - 266 ): 5 = 7
( x - 266 ) = 7 x 5
( x - 266 ) = 35
x = 35 + 266
x = 301
b) ( x - 129 ) x 4 = 36
( x - 129 ) = 36 : 4
( x - 129 ) = 9
x = 9 + 129
x = 138
c) 786 - x = 5 x 4 : 2
786 - x = 20 : 2
786 - x = 10
x = 786 - 10
x = 776
d) x + 24 : 4 x 3 = 285
x + 6 x 3 = 285
x + 18 = 285
x = 285 - 18
x = 267