Tính nhanh: a) ( 68 x 72 x 49) x ( 27 x 12 – 9 x 36 )
b) ( 25 x 50 – 125 x 10 ) x ( 1 + 2 + 3 + ……….. + 99 + 100
1/ Tính nhanh
a) ( - 4 ) x ( + 125 ) x ( - 25 ) x 6 x ( - 8 )
b) 122 x ( - 12345 ) + 12345 x ( - 78 )
c) 36 x ( - 9 ) + 9 x ( - 64 )
d) ( - 18 ) x ( 50 - 22 ) - 25 x ( 32 - 62 )
e) 1 - 2 + 3 - 4 + .... + 43 - 44 + 45
f) ( - 1 ) + 2 + ( - 3 ) + 4 + ( - 5 ) + 6 + ...... + ( - 99 ) + 100
g) 5 - 10 + 15 - 20 + 25 - .... + 105 - 110
giải gấp nha ! cảm ơn rất nhiều !
a, (-4) . (+125) . (-25) . 6 . (-8)
=[ (-4) . (-25) ] . [ (+125) . (-8) ] . 6
= 100 . (-1000) . 6
= -100 000 . 6
= -600 000
b, 122 . (-12345) + 12345 . (-78)
= 12345 . [ (-122) + (-78) ]
= 12345 . (-200)
= -2 469 000
c, 36 . (-9) + 9 . (-64)
= 9 . [ (-36) + (-64) ]
= 9 . (-100)
= -900
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) \(\dfrac{12}{7}\div x+\dfrac{2}{3}=\dfrac{7}{5}\)
\(\dfrac{12}{7}\div x=\dfrac{7}{5}-\dfrac{2}{3}\)
\(\dfrac{12}{7}\div x=\dfrac{11}{15}\)
\(x=\dfrac{12}{7}\div\dfrac{11}{15}\)
\(x=\dfrac{180}{77}\)
1: Tính nhanh :
a) 437 + 541 + 463 - 341
b) 562 + 389 - 462 + 611
c) ( 417 + 536 ) + ( 583 - 436 )
d) 325 x 6 + 6 x 560 + 115 x 6
e)133 : 7 + 154 : 7 + 413 : 7
f) 2 x 13 x 5 x 4 x 17 x 25
g) 125 x 36 x 8
h) 28 x 14 x 25
i) 125 x 31 x 72
k) 417 x 28 - 28 x 317 + 5200
l) 3 x 78 x 8 + 6 x 22 x 4 - 24 x 10
m) 3 x 128 x 12 - 4 x 28 x 9 + 18 x 100 x 2
n) 50 x 76 + 25 x 18 - 14 x 125
a)437+541+463-341
=(437+463)+(541-341)
=900+200
=1100
tính nhanh
a. 125 x 27 x 14 x 9 x 15
24 x 25 x 28 x 36 x 75
b. 0,8 x 274 x 0,3 x 0,6 x 72,2 x 4 + 3,4 x 2,4
c. ( 0,3 + 0,5 + 0,7 +...........+ 0,35) x ( 136 x 27- 68 x 6 x 9)
giúp mình mình vote 5*
Thu gọn biểu thức:
A = 10 + 11 + 12 + ... + 100
B = 10 + 12 + ... + 200
C = 11 + 13 + ... + 99
D = 1 + 4 + 7 + ... + 100
E = 1 x 2 + 2 x 3 + ... + 49 x 50
F = 1 x 2 x 2 + 2 x 3 x 4 + ... + 48 x 49 x 50
bài 1:tìm x biết
a,(125-x)+25=98
b,100:(x+20)=68:34
c,(3.x+12).5=25.4-10
d,210:(2.x-3)-20=10
a) (125 - x) + 25 = 98
125 - x = 98 - 25
125 - x = 73
x = 125 - 73
x = 52
b) 100 : (x + 20) = 68 : 34
100 : (x + 20) = 2
x + 20 = 100 : 2
x + 20 = 50
x = 50 - 20
x = 30
c) (3x + 12) . 5 = 25 . 4 - 10
(3x + 12) . 5 = 100 - 10
(3x + 12) . 5 = 90
3x + 12 = 90 : 5
3x + 12 = 18
3x = 18 - 12
3x = 6
x = 6 : 2
x = 3
d) 210 : (2x - 3) - 20 = 10
210 : (2x - 3) = 10 + 20
210 : (2x - 3) = 30
2x - 3 = 210 : 30
2x - 3 = 70
2x = 70 + 3
2x = 73
x = 73/2
a, ( 125 - x ) + 25 = 98
⇒ 125 - x = 73
⇒ x = 52.
Vậy..
b, 100 : ( x + 20 ) = 68 : 34
⇒ 100 : ( x + 20 ) = 2
⇒ x + 20 = 50
⇒ x = 30
Vậy...
c, ( 3 . x + 12 ) . 5 = 25 . 4 - 10
⇒ ( 3 . x + 12 ) . 5 = 90
⇒ 3 .x + 12 = 18
⇒ 3x = 6
⇒ x = 2.
Vậy...
d, 210 : ( 2 .x - 3 ) - 20 = 10
⇒ ( 2 .x - 3 ) - 20 = 21
⇒ 2x - 3 = 41
⇒ 2x = 44
⇒ x = 22.
Vậy..
Cho mk chỉnh lại câu cuối:
d, 210 : ( 2 .x - 3 ) - 20 = 10
⇒ 210 : ( 2 .x - 3 ) = 30
⇒ 2 . x - 3 = 7
⇒ 2x = 10
⇒ x = 5.
Vậy..
tính hợp lí
a) 135 x (-27) + 27 x 235
b) 36 x (-125) - 125 x (-46)
c) 32 x (-64) - 64 x 68
d) (145 - 45) x (-31) + 31 x (-100)
a) 135 . (-27) + 27 . 235
= 27 . (235 - 135)
= 27 . 100
= 2700
b) 36 . (-125) - 125 . (-46)
= 125 . (-36 + 46)
= 125 . 10
= 1250
c) 32 . (-64) - 64 . 68
= 64.(-32 - 68)
= 64.(-100)
= -6400
d) (145 - 45) . (-31) + 31 . (-100)
= 100 . (-31) + 31.(-100)
= 100.(-31 - 31)
= 100.(-62)
= -6200
a)
=(-135)x27+27x235
=27x[+(235+135)]
=27x31725
=856575
b)
=(-36)x125-125x(-46)
=125x[-(36+46)]
=125x(-1656)
=-207000
c)
=(-32)x64-64x68
=64x[-(68-32)]
=64x(-36)
=-(64x36)
=-2304
d)
=100x(-31)+31x(-100)
=(-100)x31+31x(-100)
=31x[-(100+100)]
=31x(-200)
=-(31x200)
=-6200
chúc học tốt nhớ tích cho tui nha
nếu tui đúng chứ tui cũng hông có chắc nữa
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
`@` `\text {Ans}`
`\downarrow`
`1,`
`a)`
`5 \times 72 \times 10 \times 2`
`= 5 \times 2 \times 10 \times 72`
`= 10 \times 10 \times 72`
`= 100 \times 72`
`= 7200`
`b)`
`40 \times 125`
`= 4 \times 10 \times 25 \times 5`
`= (5 \times 10) \times (4 \times 25)`
`= 50 \times 100`
`= 5000`
`c)`
`4 \times 2021 \times 25`
`= (4 \times 25) \times 2021`
`= 100 \times 2021`
`= 202100`
`d)`
`16 \times 6 \times 25`
`= 4 \times 4 \times 6 \times 25`
`= (4 \times 25) \times 4 \times 6`
`= 100 \times 24`
`= 2400`
`2,`
`a)`
`24 \times 57 + 43 \times 24`
`= 24 \times (57+43)`
`= 24 \times 100`
`= 2400`
`b)`
`12 \times 19 + 80 \times 12 +12`
`= 12 \times (19 + 80 + 1)`
`= 12 \times 100`
`= 1200`
`c)`
`(36 \times 15 \times 169) \div (5 \times 18 \times 13)`
`= 36 \times 15 \times 169 \div 5 \div 18 \div 13`
`= 6 \times 6 \times 3 \times 5 \times 13 \times 13 \div 5 \div 3 \times 6 \div 13`
`= (6 \div 6) \times (3 \div 3) \times (5 \div 5) \times (13 \div 13) \times 6 \times 13`
`= 6 \times 13`
`= 78`
`d)`
`(44 \times 52 \times 60) \div ( 11 \times 13 \times 15)`
`= 44 \times 52 \times 60 \div 11 \div 13 \div 15`
`= 4 \times 11 \times 13 \times 4 \times 15 \times 4 \div 11 \div 13 \div 15`
`= (11 \div 11) \times (13 \div 13) \times (15 \div 15) \times 4 \times 4 \times`
`= 4 \times 4 \times 4`
`= 64`
`3,`
`a)`
`x - 280 \div 35 = 5 \times 54`
`x - 8 = 270`
`x = 270 + 8`
`x = 278`
`b)`
`(x - 280) \div 35 = 54 \div 4`
`(x - 280) \div 35 = 13,5`
`x - 280 = 13,5 \times 35`
`x - 280 = 472,5`
`x = 472,5 + 280`
`x = 752,5`
`c)`
`(x - 128 + 20) \div 192 = 0`
`x - 128 + 20 = 0 \times 192`
`x - 128 + 20 = 0`
`x - 108 = 0`
`x = 0 + 108`
`x = 108`
`d)`
`4 \times (x + 200) = 460 + 85 \times 4`
`4 \times (x+200) = 460 + 340`
`4 \times (x+200) = 800`
`x + 200 = 800 \div 4`
`x + 200 = 200`
`x = 200 - 200`
`x = 0`
`4,`
`a)`
`7/12 - 5/12`
`= (7 - 5)/12`
`= 2/12`
`= 1/6`
`b)`
`8/11 + 19/11`
`= (8+19)/11`
`= 27/11`
`c)`
`3/8 + 5/12`
`= 9/24 + 10/24`
`= 19/24`
`d)`
`3/4 + 7/12`
`= 9/12 + 7/12`
`= 16/12`
`= 4/3`
`5,`
`a)`
`x - 6/7 = 5/2`
`x = 5/2 + 6/7`
`x = 47/14`
`b)`
`12/7 \div x + 2/3 = 7/5`
`12/7 \div x = 7/5 - 2/3`
`12/7 \div x = 11/15`
`x = 12/7 \div 11/15`
`x = 180/77`
`@` `\text {Kaizuu lv uuu}`
tính bằng hai cách
786 x ( 32 + 68 )
2904 x 15 + 2904 x 35
436 x 72 - 436 x 42
194 x ( 87 - 7 )
3332 : ( 4 x 49 )
72 : 9 : 8
( 15 x 24 ) : 6
25 x ( 36 : 9 )
C1:
a. 786 x ( 32 +68)
= 786 x 100
= 78600
b. 2904 x 15 + 2904 x 35
= 43560 + 101640
= 145200
c.436 x 72 - 436 x 42
= 31392 - 18312
= 13080
d.194 x (87-7)
= 194 x 80
=15520
e.3332 : (4x49)
= 3332 : 196
= 17
f. 72 : 9 : 8
= (72 : 9) :8
= 1
g. (15 x 24) : 6
= 360 :6
= 60
m. 25 x(36 :9)
= 25 x 4
= 100
Cách 2:
a.786 x 32 + 786 x 68
= 25152 + 53448
= 78600
b. 2904 x ( 15 + 35)
= 2904 x 50
= 145200
c.436 x (72 -42)
= 436 x 30
= 13080
d.194 x 87 - 194 x7
= 16878 - 1358
= 15520
e. 3332 : (4 x 49)
= 3332 : 4 : 49
= 833 : 49 = 17
f. 72 : 9 :8
= 72 : (9 x8)
= 72 : 72
=1
g. (15 x 24) :6
= 15 x (24 :6)
= 15 x 4
= 60
m. 25 x (36 :9)
= ( 25 x36 ):9
= 900 : 9
=100