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1.73.(8-59)-59.(8-73)
=73.8-73.59-59.8-59.73
=73.(59-59)-8.(73-59)
=73.0-8.14
=0-112
=-112
2.159.(18-59)-59.(18 - 159)
=159.18-59.159-59.18-59.159
=159.(59-59)-18.(159-59)
=159.0-18.100
=0-1800
=-1800
( -37 ) + 14 + 26 + 37 = [ ( -37 ) + 37 ] + ( 14 + 26 ) = 0 + 40 = 40
1. ( -24 ) + 6 + 10 + 24 = [ ( -24 ) + 24 ] + ( 6 + 10 ) = 0 + 16 = 16
2. 15 + 23 + ( -25 ) + ( -23 ) = [ 15 + ( -25 ) ] + [ 23 + ( -23 ) = ( -10 ) + 0 = -10
3. 60 + 33 + ( -50 ) + ( -33 ) = [ 60 + ( -50 ) ] + [ 33 + ( -33 ) ] = 10 + 0 = 10
4. ( -16 ) + ( -209 ) + ( -14 ) + 209 = [ ( -16 ) + ( -24 ) ] + [ ( -209 ) + 209 ] - ( -40 ) + 0 = -40
5.( -12 ) + ( -13 ) + 36 + ( -11 ) = [ ( -12 ) + ( -13 ) + ( -11 ) ] + 36 = ( -36 ) + 36 = 0
6. ( -16 ) + 24 + 16 - 34 = [ ( -16 ) + 16 ] + ( 24 - 34 ) = 0 + ( - 10 ) = -10
7. 25 + 37 - 48 - 25 - 37 = ( 25 - 25 ) + ( 37 - 37 ) - 48 = 0 + 0 - 48 = -48
8. 2575 + 37 - 2576 - 29 = ( 2575 - 2576 ) + ( 37 - 29 ) = ( -1 ) + 8 = 7
34 + 35 + 36 - 14 - 15 - 16 - 17 = ( 34 - 14 ) + ( 35 - 15 ) + ( 36 - 16 ) - 17 = 20 + 20 + 20 - 17 = 60 - 17 = 43
OK
- (-37)+14+26+37 = (-37+37)+(14+26)
= 0+ ( 14+26)
= 0+ 40 = 40
*1.) (-24)+6+10+24 = (-24+24)+(6+10)
= 0+ 16 = 16
2.) 15+23+(-25)+(-23) = (23+-23)+(15+-25)
= 0 + -10 = -10
3.) 60+33+(-50)+(-33) = (33+-33)+(60+(-50)
= 0+ 10 = 10
4.) (-16)+(-209)+(-14)+209 = (-209+209)+(-16+-14)
= 0+ -30 = -30
5.) (-12) +(-13)+36+(-11) = (-12+-13+-11)+36
= -36 + 36 = 0
6.) -16 +24 +16-34 = (-16+16)+(24-34)
= 0+ -10 = -10
8.) 2575 +37-2575-29 =(2575-2575)+(37 -29)
= 0 + 8 = 8
- 34 +35+36+37 -14-15-16-17
= (34-14)+(35-15)+(36-16)+(37-17)
= 10+10+10+10
= 10 . 4 = 40
1)C= 1/5+1/10+1/20+1/40+...+1/1280
\(=\frac{1}{5}\left(1+\frac{1}{2}+\frac{1}{2^2}+...+\frac{1}{2^8}\right)\)
Đặt cái trong ngoặc là A ta có:\(2A=2+1+...+\frac{1}{2^7}\)
\(2A-A=\left(2+1+...+\frac{1}{2^7}\right)-\left(1+\frac{1}{2}+...+\frac{1}{2^8}\right)\)
\(A=2-\frac{1}{2^8}\).Thay A vào ta được:\(C=\frac{1}{5}\left(2-\frac{1}{2^8}\right)=\frac{1}{5}\cdot\frac{511}{256}=\frac{511}{1280}\)
2)D= 2/1*3+2/3*5+2/5*10+2/7*9+2/9*11+2/11*18+2/13*15
\(=1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+...+\frac{1}{13}-\frac{1}{15}\)
\(=1-\frac{1}{15}\)
\(=\frac{14}{15}\)
3)E= 4/3*7+4/7*11+4/11*15+4/15*19+4/19*23+4/23*27
\(=\frac{1}{3}-\frac{1}{7}+\frac{1}{7}-\frac{1}{11}+...+\frac{1}{23}-\frac{1}{27}\)
\(=\frac{1}{3}-\frac{1}{27}\)
\(=\frac{8}{27}\)
4)G= 1/2+1/6+1/12+1/20+1/30+1/42+...+1/110
\(=\frac{1}{1.2}+\frac{1}{2.3}+...+\frac{1}{10.11}\)
\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+...+\frac{1}{10}-\frac{1}{11}\)
\(=1-\frac{1}{11}\)
\(=\frac{10}{11}\)
5)H= 3/1*2+3/2*3+3/3*4+3/4*5+...+3/9*10
\(=3\left(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+...+\frac{1}{9}-\frac{1}{10}\right)\)
\(=3\left(1-\frac{1}{10}\right)\)
\(=3\times\frac{9}{10}\)
\(=\frac{27}{10}\).Lần sau bạn đăng ít một thôi nhé
1) (3x + 9)(3x - 6) = 0
=> \(\orbr{\begin{cases}3x+9=0\\3x-6=0\end{cases}}\)
=> \(\orbr{\begin{cases}3x=-9\\3x=6\end{cases}}\)
=> \(\orbr{\begin{cases}x=-3\\x=2\end{cases}}\)
Vậy ...
b) (2x + 15) - 25 = 47 - (10 - x)
=> 2x - 10 = 37 + x
=> 2x - x = 37 + 10
=> x = 47
3, tương tự
4) |4 - 3x| = 8
=> \(\orbr{\begin{cases}4-3x=8\\4-3x=-8\end{cases}}\)
=> \(\orbr{\begin{cases}3x=-4\\3x=12\end{cases}}\)
=> \(\orbr{\begin{cases}x=-\frac{4}{3}\\x=4\end{cases}}\)
Vì x là số nguyên nên ...
còn lại tương tự
1,2,3 ko bt lm nhé
4. \(4\cdot\left(3x-4\right)-2=18\\ 12x-16-2-18=0\\ 12x=-36\\ x=-2\)
5. ( 105-x)/25=30+1
(105-x) / 32 = 1+1
( 105-x) / 32 = 2
105-x=64
x=105-64
x=41
6. 2x - 138=22*32
2x-138=36
2x=138+36
2x=174
x=87
7.(6x-39)*28=5628
6x-39=201
6x=240
x=40
8. (9x+2)*3=60
9x+2=20
9x=18
x=2
9. (26-3x)/5+71=75
(26-3x) /5=4
26-3x = 20
3x=6
x=2
Trả lời :
1, |-165| + |70| - 400 = 165 + 70 - 400 = 235 - 400 = -165
2, (-3) + 4 + 18 = 1 + 18 = 19
3, ( - 10 ) + ( -9 ) + 6 = -19 + 6 = -13
4, 5 - 10 + 4 = -1
5, (-15) + |-45| + 15 = [ ( - 15 ) + 15 ] + |-45| = 0 + 45 = 45
6, 13 + |-128| - 2 = 13 + 128 - 2 = 139
7, ( - 115 ) - 18 + 115 = [ (-115) + 115 ] - 18 = 0 - 18 = -18
8, 26 + 59 + 145 - 59 - 26 = ( 26 - 26 ) + (59 - 59 ) + 145 = 0 + 0 = 145 = 145
Have a nice dayy !!
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