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( 35 - 2x ) . 4 + 26 = 38
( 35 - 2 . x ) . 4 = 38 - 26
( 35 - 2 . x ) . 4 = 12
( 35 - 2 . x ) = 12 : 4
( 35 - 2 . x ) = 3
2 . x = 35 - 3
2 . x = 32
x = 32 : 2
x = 16
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4(x+41)=400
=>x+44=400 : 4
x+41=100
=> x=100-41
x=59
\(4\left(x+41\right)=400\)
\(\Rightarrow4x+164=400\)
\(\Rightarrow4x=400-164=236\)
\(\Rightarrow x=236:4=59\)
k mk nhé,sau đó mk sẽ kb vs bn
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\(2.x-15=11\)
\(2x=11+15\)
\(2x=26\)
\(x=26:2\)
\(x=13\)
\(b,4.\left(2-x\right)-5\left(3-x\right)=-12\)
\(8-4x-15+5x=-12\)
\(x-7=-12\)
\(x=-12+7\)
\(x=-5\)
\(c,\left|x-7\right|+13=25\)
\(\left|x-7\right|=25-13\)
\(\left|x-7\right|=12\)
\(\Rightarrow\orbr{\begin{cases}x-7=12\\x-7=-12\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=19\\x=-5\end{cases}}\)
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b)
Ta có :
A = 2017 x 2017 = 2016 x 2017 + 2017
B = 2016 x 2018 = 2016 x 2017 + 2016
=> A > B
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\(A=\frac{4}{7\cdot9}+\frac{4}{9\cdot11}+...+\frac{4}{59\cdot61}=2\cdot\left(\frac{2}{7\cdot9}+\frac{2}{9\cdot11}+...+\frac{2}{59\cdot61}\right)\)
\(=2\cdot\left(\frac{1}{7}-\frac{1}{9}+\frac{1}{9}-\frac{1}{11}+...+\frac{1}{59}-\frac{1}{61}\right)=2\cdot\left[\left(\frac{1}{7}-\frac{1}{61}\right)+\left(\frac{1}{9}-\frac{1}{9}\right)+...+\left(\frac{1}{59}-\frac{1}{59}\right)\right]\)\(=2\cdot\left[\left(\frac{61}{427}-\frac{7}{427}\right)+0+...+0\right]=2\cdot\frac{54}{427}=\frac{108}{427}\)
Cách làm thì đúng rồi nhưng mk k chắc tính đúng, nhẩm thôi
xl bạn nhé nhưng bạn hiểu nhầm r ( chắc do mình ) nó là \(\frac{4\cdot9}{7}\)nhé bạn =))
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1. Tìm x
a, -( x - 61 ) + |+32| = 9
-x + 61 + 32 = 9
-x + 93 = 9
-x = -84
x = 84
b, -86 + |x-15| = (-3)2
|x-15| = 9 + 86
|x-15| = 95
TH1: x - 15 = 95
x = 110
TH2: x - 15 = -95
x = -80
2. Thực hiện phép tính
a, (-8).(-9) + (-14):2 - (-8)2
= 72 - 7 - 64
= 1
b, (-10).(-7) + 306:(-9) - (-5)3
= 70 - 34 + 125
= 161
c, (-4)3 + (-11).(+8) - (-15):(-5)
= -64 - 88 - 3
= -155
d, (-13).(+7) - (-20):(+4) + (-5)2
= -91 + 5 + 25
= -61
Chúc bạn học tốt !
( 7 . x - 2 ) . 4 + 13 = 61
( 7 . x - 2 ) . 4 = 61 - 13
( 7 . x - 2 ) . 4 = 48
( 7 . x - 2 ) = 48 : 4
7 . x - 2 = 12
7 . x = 12 + 2
7 . x = 14
x = 14 : 7
x = 2
( 7 . x - 2 ) . 4 + 13 = 61
( 7 . x - 2 ) . 4 = 61 - 13
( 7 . x - 2 ) . 4 = 48
7 . x - 2 = 48 : 4
7 . x - 2 = 12
7 . x = 12 + 2
7 . x = 14
x = 14 : 7
x = 2
Vậy x= 2