Tính nhanh
a, \(-57\left(75-36\right)-75\left(36-57\right)\)
b, \(19-42\left(-19\right)+38.5\)
- Pờ li hép mi :<
a: \(=-57\cdot75+57\cdot36-75\cdot36+75\cdot57\)
\(=36\left(57-75\right)=-18\cdot36=-648\)
b: \(=19+19\cdot42+19\cdot10\)
\(=19\cdot62=1178\)
Tính nhanh
a, −57(75−36)−75(36−57)
b, 19−42(−19)+38.5
Tìm x
a,7x(x-10)=0
b, (4-x) . ( 2x+6)=0
c, -12(x-5) + 7 . ( 3-x ) =5
Bài 2: Tìm x
a, \(7x\left(x-10\right)=0\)
\(\Rightarrow x\left(x-10\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x=0\\x-10=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=0\\x=10\end{matrix}\right.\)
b, \(\left(4-x\right)\left(2x+6\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}4-x=0\\2x+6=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=4\\x=-3\end{matrix}\right.\)
c, \(-12\left(x-5\right)+7\left(3-x\right)=5\)
\(\Rightarrow-12x+60+21-7x=5\)
\(\Rightarrow-19x=5-60-21\)
\(\Rightarrow-19x=-76\Rightarrow x=4\)
Chúc bạn học tốt!!!
1)tính hợp lý
a) -57.(75-36)-75.(36-57)
b) (37-7).(-9)+(-17-13).21
2)tìm x E Z
a) (-x+821+534)=499+(x-84)
b) x+52 = (400-9x)-448
a) 42-x=5
b) 15.(x+4)=75
c) 27+3x=9^8.9^7
d) x+18=12
e) 2x-15=-19
f) 36 :(x^3-12)=-3
g)x+15=35
h) 2x-13=3^2
a) 42 - x = 5
x = 42 - 5
x = 37
b) 15.(x + 4) = 75
x + 4 = 75 : 15
x + 4 = 5
x = 5 - 4
x = 1
d) x + 18 = 12
x = 12 - 18
x = -6
e) 2x - 15 = -19
2x = (-19) + 15
2x = -4
x = -4 : 2
x = -2
f) 36 : (x^3 - 12) = -3
x^3 - 12 = 36 : (-3)
x^3 - 12 = -12
x^3 = 0
=> x = 0
g)x + 15 = 35
x = 35 - 15
x = 20
h) 2x - 13 = 3^2
2x - 13 = 9
2x = 9 + 13
2x = 22
x = 22 : 2
x = 11
a) 42-x=5
x=42-5
x= 37
b)15*(x+4)=75
x+4=75:15
x+4=5
x =5-4
x = 1
a) 42 - x = 5
x = 42 - 5
x = 37
b) 15.(x + 4) = 75
x + 4 = 75 : 15
x + 4 = 5
x = 5 - 4
x = 1
d) x + 18 = 12
x = 12 - 18
x = -6
e) 2x - 15 = -19
2x = (-19) + 15
2x = -4
x = -4 : 2
x = -2
f) 36 : (x^3 - 12) = -3
x^3 - 12 = 36 : (-3)
x^3 - 12 = -12
x^3 = 0
=> x = 0
g)x + 15 = 35
x = 35 - 15
x = 20
h) 2x - 13 = 3^2
2x - 13 = 9
2x = 9 + 13
2x = 22
x = 22 : 2
x = 11
bài 1: tính hợp lí
a) 5 x 72 x 10 x 2 b) 40 x 125 c) 4 x 2021 x 25 d) 16 x 6 x 25
bài 2: tính nhanh
a) 24 x 57 + 43 x 24 b) 12 x 19 + 80 x 12 +12
c) (36 x 15 x 169) : (5 x 18 x13) d) (44 x 52 x 60) : ( 11 x 13 x 15)
bài 3: tìm X
a) X - 280 : 35 = 5 x 54 b) ( X - 280) : 35 = 54 : 4
c) ( X - 128 + 20 ) : 192 = 0 d) 4 x ( X + 200) = 460 + 85 x 4
bài 4: thực hiện phép tính
a) 7/12 - 5/12 b) 8/11 + 19/11 c) 3/8 + 5/12 d) 3/4 + 7/12
bài 5: tìm x
a) X - 6/7 = 5/2 b) 12/7 : X + 2/3 = 7/5
Bài 1
a) \(5\times72\times10\times2=\left(5\times2\times10\right)\times72=100\times72=7200\)
b) \(40\times125=5\times\left(8\times125\right)=5\times1000=5000\)
c) \(16\times6\times25=4\times4\times6\times25=\left(4\times6\right)\times\left(4\times25\right)=24\times100=2400\) Bài 2:
a) \(24\times57+43\times24=24\times\left(57+43\right)=24\times100=2400\)
b) \(12\times19+80\times12+12=12\times\left(19+80+1\right)=12\times100=1200\)
c) \(\left(36\times15\times169\right)\div\left(5\times18\times13\right)\)
\(=\left(18\times2\times3\times5\times13\times13\right)\div\left(5\times18\times13\right)\)
\(=\left(2\times3\times13\right)\times\left(18\times5\times13\right)\div\left(5\times18\times13\right)\)
\(=2\times3\times13\)
\(=78\)
d) \(\left(44\times52\times60\right)\div\left(11\times13\times15\right)\)
\(=\left(4\times11\times4\times13\times4\times15\right)\div\left(11\times13\times15\right)\)
\(=\left(4\times4\times4\right)\times\left(11\times13\times15\right)\div\left(11\times13\times15\right)\)
\(=4\times4\times4\)
\(=64\)
Bài 3:
a) \(x-280\div35=5\times54\)
\(x-8=270\)
\(x=270+8\)
\(x=278\)
b) \(\left(x-280\right)\div35=54\div4\)
\(\left(x-280\right)\div35=\dfrac{27}{2}\)
\(x-280=\dfrac{27}{2}\times35\)
\(x-280=\dfrac{945}{2}\)
\(x=\dfrac{945}{2}+280\)
\(x=\dfrac{1505}{2}\)
c) \(\left(x-128+20\right)\div192=0\)
\(x-128+20=0\times192\)
\(x-128+20=0\)
\(x-128=0-20\)
\(x-128=-20\)
\(x=-20+128\)
\(x=108\)
d) \(4\times\left(x+200\right)=460+85\times4\)
\(4\times\left(x+200\right)=460+340\)
\(4\times\left(x+200\right)=800\)
\(x+200=800\div4\)
\(x+200=200\)
\(x=200-200\)
\(x=0\)
Bài 4:
a) \(\dfrac{7}{12}-\dfrac{5}{12}=\dfrac{2}{12}=\dfrac{1}{6}\)
b) \(\dfrac{8}{11}+\dfrac{19}{11}=\dfrac{27}{11}\)
c) \(\dfrac{3}{8}+\dfrac{5}{12}=\dfrac{9}{24}+\dfrac{10}{24}=\dfrac{19}{24}\)
d) \(\dfrac{3}{4}+\dfrac{7}{12}=\dfrac{9}{12}+\dfrac{7}{12}=\dfrac{16}{12}=\dfrac{4}{3}\)
Bài 5:
a) \(x-\dfrac{6}{7}=\dfrac{5}{2}\)
\(x=\dfrac{5}{2}+\dfrac{6}{7}\)
\(x=\dfrac{47}{14}\)
b) \(\dfrac{12}{7}\div x+\dfrac{2}{3}=\dfrac{7}{5}\)
\(\dfrac{12}{7}\div x=\dfrac{7}{5}-\dfrac{2}{3}\)
\(\dfrac{12}{7}\div x=\dfrac{11}{15}\)
\(x=\dfrac{12}{7}\div\dfrac{11}{15}\)
\(x=\dfrac{180}{77}\)
a, 35 . 34 + 35 . 86 + 65 . 75 + 65 . 45
b, 11 + 12 +...+ 20
c , 8 . 9 . 11 + 6 . 20 . 12 + 19 . 4 . 18
d, 143 . ( 57 - 36 ) - 57 ( 143 - 36 )
a , 35 * 34 + 35 * 86 + 65 * 75 + 65 * 45
= 35 * ( 34 + 86 ) + 65 * (75 + 45 )
= 35 * 120 + 65 * 120
= 120 * ( 35 + 65 )
= 120 * 100
= 12000
b , 11+12 + ...+ 20
= ( 11 +19 ) +( 12 + 18 ) + ( 13 + 17 ) + ( 14 + 16 ) +15 +20
= 30 + 30 + 30 + 30 + 15 + 20
= 30 * 4 + 35
= 120 + 35
= 155
c , 8 * 9 * 11 + 6 * 20 * 12 + 19 * 4 * 18
= 792 + 1440 + 1368
=3600
d , 143 * ( 57 - 36 ) - 57 * ( 143 - 36 )
= 143 * 57 - 143 * 36 - 57 * 143 - 57 * 36
= 143 * 57 - 57 * 143 - 143 * 36 - 57 * 36
= 0 - ( 143 - 57 )
= 0 - 86
= - 86
a) \(35.34+35.86+65.75+65.45\)
\(=35.\left(34+86\right)+65.\left(75+45\right)\)
\(=35.120+65.120\)
\(=\left(35+65\right).120\)
\(=100.120\)
\(=12000\)
b) \(11+12+...+20\)
Số số hạng của dãy là : (20 - 11) : 1 + 1 = 10 (số)
Tổng của dãy là : (20 + 1) x 10 : 2 = 105
c) \(8.9.11+6.20.12+19.4.18\)
\(=\left(8.9\right).11+\left(6.12\right).20+\left(4.18\right).19\)
\(=72.11+72.20+72.19\)
\(=72.\left(11+20+19\right)\)
\(=72.50\)
\(=3600\)
d) \(143.\left(57-36\right)-57.\left(143-36\right)\)
\(=143.57-143.36-57.143-57.36\)
\(=\left(143.57-57.143\right)-\left(143.36-57.36\right)\)
\(=0-36.\left(143-57\right)\)
\(=0-36.86\)
\(=0-3096\)
\(=-3096\)
_Chúc bạn học tốt_
a) 35.34 + 35.86 + 65 . 75 + 65 .45 = 35(34+86) + 65(75+45) = 35.120 + 65.120 = (35+65).120 = 100.120 = 12000
b)11+12+...+20 = (11+19)+(12+18)+(13+17)+(14+16)+20+15=30.4+35=120+35=155
c)8.9.11 +6.20.12+19.4.18 = 72(11+20+19) = 72 . 50 = 3600
d) 143 . (57 - 36 ) - 57.(143 - 36) = 143 . 57 - 143. 36 - 57 . 143 - 57 . 36 = 143(57 - 57) - 36(143 - 57) = 0 - 36.86 = -3096
a) ( x . 7 + 8 ) : 5 = 10
b) ( x + 5 ) . 19 : 13 = 57
c) 4 . ( 36 - 4 . x ) = 64
d) 7,6 : 1,9 . x = 3,2
e) ( x : 2 + 50 ) : 5 = 12
g) 280 : ( 17 + 3 . x ) = 4
h ) 6. ( 28 - 8 . x ) = 72
i) ( x - 15 ) : 3 : 12 = 6
giúp mh với nha các bn
a) (x.7 + 8) : 5 = 10
x.7 + 8 = 10.5
x.7 + 8 = 50
x.7 = 50 - 8
x.7 = 42
x = 42 : 7
x = 6
b) (x + 5).19 : 13 = 57
(x + 5).19 = 57 . 13
(x + 5).19 = 741
x + 5 = 741 : 19
x + 5 = 39
x = 39 - 5
x = 34
c) 4.(36 - 4.x) = 64
36 - 4x = 64 : 4
36 - 4x = 16
4x = 36 - 16
4x = 20
x = 20 : 4
x = 5
d) 7,6 : 19 . x = 3,2
0,4 . x = 3,2
x = 3,2 : 0,4
x = 8
e) (x : 2 + 50) : 5 = 12
x : 2 + 50 = 12 . 5
x : 2 + 50 = 60
x : 2 = 60 - 50
x : 2 = 10
x = 10 . 2
x = 20
g) 280 : (17 + 3.x) = 4
17 + 3x = 280 : 4
17 + 3x = 70
3x = 70 - 17
3x = 53
x = 53/3
h) 6.(28 - 8.x) = 72
28 - 8x = 72 : 6
28 - 8x = 12
8x = 28 - 12
8x = 16
x = 16 : 8
x = 2
i) (x - 15) : 3 : 12 = 6
(x - 15) : 3 = 6 . 12
(x - 15) : 3 = 72
x - 15 = 72 . 3
x - 15 = 216
x = 216 + 15
x = 231
6.Tính thuận tiện 142 × 36 + 57 × 36 +36 × 75 + 36
\(=36\left(142+57+75+1\right)=36\cdot275=9900\)
Bạn tham khảo:
142 x 36 + 57 x 36 + 36 x 75 + 36
= 36 x (142 + 57 + 75 + 1)
= 36 x 275
= 9900
tìm x
a) (3x+4):12+17=19
b) 57-4 : (2x-1 )=53
c) 45:(2x+1 )-3=0
d )36+72 : (x+1)=396
e ) 470 -(2x+3)*11=217
(3x+4):12+17=19
=>3x+4:12=19-17
=>(3x+4):12=2
=>3x+4=2x12
=>3x+4=24
=>3x=24-4
=>3x=20
=>x=20/3
tíc mình nha
trời tức quá
lm xong hết oy mà nhấn ngay chỗ Hủy thế là xong tiu nguyên 1 bài
tốn công từ nãy tới h :(( huhuhuhuhuh
chắc tức chết mất :((((
a ) ( 3x + 4 ) : 12 + 17 = 19
( 3x + 4 ) : 12 = 19 - 17
( 3x + 4 ) : 12 = 2
3x + 4 = 2.12
3x + 4 = 24
3x = 24 - 4
3x = 20
x = 20 : 3
x = \(\frac{20}{3}\)
b ) 57 - 4 : ( 2x - 1 ) = 53
53 : ( 2x - 1 ) = 53
2x - 1 = 53 : 53
2x - 1 = 1
2x = 1 + 1
2x = 2
x = 2 : 2
x = 1
c ) 45 : ( 2x + 1 ) - 3 = 0
45 : ( 2x + 1 ) = 0 + 3
45 : ( 2x + 1 ) = 3
2x + 1 = 45 : 3
2x + 1 = 15
2x = 15 - 1
2x = 14
x = 14 : 2
x = 7
d ) 36 + 72 : ( x + 1 ) = 396
108 : ( x + 1 ) = 396
x + 1 = 108 : 396
x + 1 = 0,27...
x = 0,27 + 1
x = 1,27
e ) 470 - ( 2x + 3 ) * 11 = 217
( 2x + 3 ) * 11 = 470 - 217
( 2x + 3 ) * 11 = 253
2x + 3 = 253 : 11
2x + 3 = 23
2x = 23 - 3
2x = 20
x = 20 : 2
x = 10
