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A. 7 + 48 : x = 45 : 5 = 9 => 48 : x = 9 - 7 = 2 => x = 48 : 2 = 24.
\(5\left(7+48:x\right)=45\)
\(\Leftrightarrow\left(7+48x\right)=9\)
\(\Leftrightarrow4x=2\)
\(\Leftrightarrow x=2\)
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\(5^2x-3.2.5^2=5^2.3\)
\(\Leftrightarrow5x^2-3-2.5^2=75\)
\(\Leftrightarrow5x^2-3-50=75\)
\(\Leftrightarrow5x^2-3=125\)
\(\Leftrightarrow5x^2=128\)
\(\Leftrightarrow x^2=\frac{128}{5}\)
\(\Leftrightarrow\orbr{\begin{cases}x=\frac{128}{5}\\x=-\frac{128}{5}\end{cases}}\)
___________________
\(2+x:5=0\)
\(\Leftrightarrow x:5=-2\)
\(\Leftrightarrow x=-10\)
\(10+2x=16\)
\(\Leftrightarrow2x=6\)
\(\Leftrightarrow x=3\)
1) = 35 . 18 - 35 . 18 = 0
2) = 45 - 5 . 12 + 5 . 9 = 45 - 60 + 45 = 30
3) = 24 . 16 - 24 . 5 - 16 . 24 - 16 . 5
= (24 . 16 - 16 . 24) - 5 (24 - 16)
= 0 - 5 . 8 = 0 - 40 = -40
4) = 29 . 19 - 29 . 13 - 19 . 29 - 19 . 13
= (29 . 19 - 29 . 19) - 13 (29 - 19)
= 0 - 13 . 10 = 0 - 130 = -130
5) = 31 . (-18) + 31 . (-81) - 31 . 1
= 31 [(-18) + (-81) - 1]
= 31 . (-100) = -3100
6) = (-12) . 47 + (-12) . 52 + (-12). 1
= (-12) . (47 + 52 + 1)
= (-12) . 100 = -1200
7) = 13 . 45 - 3 . 45
= 45 (13 - 3)
= 45 . 10 = 450
8) = (-48) + 48 . (-78) + 48 . (-21)
= (-48) . 1 + 48 . (-78) + 48 . (-21)
= 48 . (-1) + 48 . (-78) + 48 . (-21)
= 48 . [(-1) + (-78) + (-21)]
= 48 . (-100) = -4800
1) 35x18-5x7x18
= 35x18-35x18
= 35x(18-18)
= 35x0=0
3) 24.(16-5)-16.(24-5)
= 24.16-24.5-16.24-16.5
=[24.16-16.24]-[24.5-16.5]
= [ 24. (16-16)]- [(24-16).5]
= [24.0]-[8.5]
= 0-40=-40
4) 29.(19-13)-19.(29-13)
=29.19-29.13-19.29-19.13
=[ 29.19-19.29]-[ 29.13-19.13]
= [ 29.(19-19)]-[(29-19).13]
=[29.0]-[10.13]
= 0-130= -130
5) 31.(-18)+31.(-81)-31
= 31.(-18)+31.(-81)-31.1
= 31.[(-18)+(-81)-1]
=31.(-100)
= -3100
6);7);8 tương tự 4);5);6)
5.(7+48:x)=45
(7+48:x)=45:5
(7+48:x)=9
48:x=9-7
48:x=2
x=48:2
x=24
a) 3x - 75 = 45 + 3(-25)
=> 3x - 75 = 45 - 75
=> 3x = 45 - 75 + 75
=> 3x = 45
=> x = 45 : 3
=> x = 15
b) 2(-7) - 11 = 6x + 17
=> -14 - 11 = 6x + 17
=> -25 = 6x + 17
=> 6x = -25 - 17
=> 6x = -42
=> x = -42 : 6
=> x = -7
c) |x + 2| = 5
=> \(\orbr{\begin{cases}x+2=5\\x+2=-5\end{cases}}\)
=> \(\orbr{\begin{cases}x=3\\x=-7\end{cases}}\)
Vậy ..
d) -4.|x - 3| = -48
=> |x - 3| = -48 : (-4)
=> |x - 3| = 12
=> \(\orbr{\begin{cases}x-3=12\\x-3=-12\end{cases}}\)
=> \(\orbr{\begin{cases}x=15\\x=-9\end{cases}}\)
Vậy ...
Bài 2:
a, 7,2: 2,4.\(x\) = 45
3.\(x\) = 45
\(x\) = 45: 3
\(x\) = 15
b, 9,15.\(x\) + 2,85.\(x\) = 48
\(x\).( 9,15 + 2,85) = 48
12\(x\) = 48
\(x\) = 48: 12
\(x\) = 4
c) (x.3 + 4) : 5 = 8
x.3 + 4 = 8 x 5
x.3 + 4 = 40
x.3 = 40 - 4
x.3 = 36
x = 36 : 3
x = 12
1) 35.18-5.7.28
=630-5.7.28
= 630-980
=630+(-980)
=-(980-630)
=-350
5(7 + 48 : x) = 45
7 + 48 : x = 45 : 5
7 + 48 : x = 9
48 : x = 9 - 7
48 : x = 2
x = 48 : 2
x = 24
Vậy x = 24
Hok tốt nhé bn!
\(5.\left(7+\frac{48}{x}\right)=45\)
\(7+\frac{48}{x}=45:5\)
\(7+\frac{48}{x}=9\)
\(\frac{48}{x}=9-7=2\)
\(\Rightarrow x=\frac{48}{2}=24\)