1 , Làm theo mẫu:
43/5=86/10=8,6
2/25=
111/125=
23/8=
76/4=
42/25
370/50=
Làm theo mẫu:
43/5=86/10=8,6
2/25=
111/125=
23/8=
76/4=
42/25
370/50=
2/25=4/50=0,08
111/125=222/250=0,888
23/8=46/16=2,875 76/4=152/8=19 42/25=84/50=1,68 370/50=740/100=7,4
Làm theo mẫu:
43/5=86/10=8,6
2/25=
111/125=
23/8=
76/4=
42/25
370/50=
2/25=4/50=0,08
111/125=222/250=0,888
23/8=46/16=2,875 76/4=152/8=19 42/25=84/50=1,68 370/50=740/100=7,4
Làm theo mẫu
43/15 = 86/10 = 8,6
9/5 = .............................................
2/25 = ...........................................
111/125 = ......................................
23/8 = ...........................................
76/4 = ...........................................
42/25 = ........................................
370/50 = ......................................
\(\frac{9}{5}=\frac{18}{10}=1,8\)
\(\frac{2}{25}=\frac{8}{100}=0,08\)
\(\frac{111}{125}=\frac{888}{1000}=0.888\)
\(\frac{23}{8}=\frac{2875}{1000}=2,875\)
\(\frac{76}{4}=\frac{1900}{100}=19\)
\(\frac{9}{5}=\frac{18}{10}=1,8\)
\(\frac{2}{25}=\frac{8}{100}=0,08\)
\(\frac{111}{125}=\frac{111.8}{125.8}=\frac{888}{1000}=0,888\)
\(\frac{76}{4}=19\)
\(\frac{23}{8}=\frac{23.125}{8.125}=\frac{2875}{1000}=2,875\)
\(\frac{42}{25}=\frac{42.4}{25.4}=\frac{168}{100}=1,68\)
\(\frac{370}{50}=\frac{37}{5}=\frac{37.2}{5.2}=\frac{74}{10}=7,4\)
làm theo mẫu
43/15 = 86/10=8,6
9/5 =
2/25 =
23/8 =
76/4 =
42/25 =
9/5 =18/10=1,8
2/25 =8/100=0,08
23/8 =2874/1000=2,874
76/4 =1900/100=19
42/25 =168/100=1,68
9/5 = 18/10 = 1,8
2/25 = 8/100 = 0,08
23/8 = 2875/1000 = 2,875
76/4 = 1900/100 = 19,00 = 19
42/25 = 168/100 = 1,68
9/5 =\(\dfrac{90}{50}=1,8\)
2/25 =\(\dfrac{20}{250}=0,08\)
23/8 =\(\dfrac{23}{8}=2,875\)
76/4 =\(\dfrac{76}{40}=\dfrac{19}{10}\)
42/25 =\(\dfrac{420}{250}=1,68\)
tính 1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20+21+22+23+24+25+26+27+28+29+30+31+32+33+34+35+36+37+38+39+40+41+42+43+44+45+46+47+48+49+50-999-888-777-666-555-444-333-222-111
nhanh nhé
1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20+21+22+23+24+25+26+27+28+29+30+31
+32+33+34+35+36+37+38+39+40+41+42+43+44+45+46+4
7+48+49+50-999-888-777-666-555-444-333-222-111= -3720
1 * 2 * 3 * 4 * 5 * 6 * 7 * 8 * 9 * 10 * 11 * 12 * 13 * 14 * 15 * 16 * 17 * 18 * 19 * 20 * 21 * 22 * 23 * 24 * 25 * 26 * 27 * 28 * 29 * 30 * 31 * 32 * 33 * 34 * 35 * 36 * 37 * 38 * 39 * 40 * 41 * 42 * 43 * 44 * 45 * 46 * 47 * 48 * 49 * 50 * 51 * 52 * 53 * 54 * 55 * 56 * 57 * 58 * 59 * 60 * 61 * 62 * 63 * 64 * 65 * 66 * 67 * 68 * 69 * 70 * 71 * 72 * 73 * 74 * 75 * 76 * 77 * 78 * 79 * 80 * 81 * 82 * 83 * 84 * 85 * 86 * 87 * 88 * 89 * 90 * 91 * 92 * 93 * 94 * 95 * 96 * 97 * 98 * 99 * 100 bằng bao nhiêu?
1. Tính hợp lí nếu có thể :
a) 125 + 80 + 375 + 220
b) 25.11.8.4.125
c) 18.74 + 18.27 - 18
d) 75 . 23 + 75 . 77 - 500
e) 150 : [25.(18-42)]
f) 125 . 23 . 2 . 8 . 50
g) 235 + 88 + 165 + 12
h) 71 . 32 + 71 . 68 - 1100
i) 67 : 66 + 43 .2 - 240
j) 546 - 6. [158 : (30 + 72)]
k) 268 + 147 + 132 + 253
2. Tìm số tự nhiên x, biết :
a) 7 . x = 707
b) 6x + 5 = 47
c) 35 : (x+1) = 7
d) 12 + (29 - 3x) = 35
e) 2.4x + 101 = 138
f) 7 . x = 140
g) 7 . (15 - x) + 14 = 84
h) 3x . 5 - 15 = 390
3. Tìm số tự nhiên n , biết :
(n+11) chia hết cho (n+1)
1.
a) \(125+80+375+220\)
\(=\left(125+375\right)+\left(80+220\right)\)
\(=500+300\)
\(=800\)
b) \(25.11.8.4.125\)
\(=\left(25.4\right).\left(8.125\right).11\)
\(=100.1000.11\)
\(=1100000\)
c) \(18.74+18.27-18\)
\(=18.\left(74+27-1\right)\)
\(=18.100\)
\(=1800\)
d) \(75.23+75.77-500\)
\(=75.\left(23+77\right)-500\)
\(=75.100-500\)
\(=7500-500\)
\(=7000\)
e) \(150:\left[25.\left(18-4^2\right)\right]\)
\(=150:\left[25.\left(18-16\right)\right]\)
\(=150:\left[25.2\right]\)
\(=150:50\)
\(=3\)
f) \(125.23.2.8.50\)
\(=\left(125.8\right).\left(2.50\right).23\)
\(=1000.100.23\)
\(=2300000\)
g) \(235+88+165+12\)
\(=\left(235+165\right)+\left(88+12\right)\)
\(=400+100\)
\(=500\)
h) \(71.32+71.68-1100\)
\(=71.\left(32+68\right)-1100\)
\(=71.100-1100\)
\(=7100-1100\)
\(=6000\)
i) \(6^7:6^6+4^3.2-24^0\)
\(=6+64.2-1\)
\(=6+128-1\)
\(=133\)
j) \(546-6.\left[158:\left(30+7^2\right)\right]\)
\(=546-6.\left[158:\left(30+49\right)\right]\)
\(=546-6.\left[158:79\right]\)
\(=546-6.2\)
\(=546-12\)
\(=534\)
k) \(268+147+132+253\)
\(=\left(268+132\right)+\left(147+253\right)\)
\(=400+400\)
\(=800\)
2.
a) \(7x=707\)
\(x=707:7\)
\(x=101\)
b) \(6x+5=47\)
\(6x=47-5\)
\(6x=42\)
\(x=42:6\)
\(x=7\)
c) \(35:\left(x+1\right)=7\)
\(x+1=35:7\)
\(x+1=5\)
\(x=5-1\)
\(x=4\)
d) \(12+\left(29-3x\right)=35\)
\(29-3x=35-12\)
\(29-3x=23\)
\(3x=29-23\)
\(3x=6\)
\(x=6:3\)
\(x=2\)
e) \(2.4^x+10^1=138\)
\(2.4^x=138-10\)
\(2.4^x=128\)
\(4^x=128:2\)
\(4^x=64=4^3\)
\(\Rightarrow x=3\)
f) \(7x=140\)
\(x=140:7\)
\(x=20\)
g) \(7\left(15-x\right)+14=84\)
\(7\left(15-x\right)=84-14\)
\(7\left(15-x\right)=70\)
\(15-x=70:7\)
\(15-x=10\)
\(x=15-10\)
\(x=5\)
h) \(3^x.5-15=390\)
\(3^x.5=390+15\)
\(3^x.5=405\)
\(3^x=405:5\)
\(3^x=81=3^4\)
\(\Rightarrow x=4\)
3.
Ta có:
\(\Rightarrow n+11⋮n+1\)
\(\Rightarrow n+1+10⋮n+1\)
\(\Rightarrow10⋮n+1\) hay \(n+1\inƯ\left(10\right)=\left\{-10;-5;-2;-1;1;2;5;10\right\}\)
\(\Rightarrow\) \(n\in\left\{-11;-6;-3;-2;0;1;4;9\right\}\)
Vì \(n\in N\) nên \(n\in\left\{0;1;4;9\right\}\)
Caau1 thực hiện phép tính
1) (-25).8.(-4).(-125)
2) 30.(-5-10)
3) 43.(53-81)+53.(81-43)
4) (-6)².(-17)+23.(-36)-72.30
1) (-25).8.(-4).(-125)
= [(-25).4].[(-125).8]
=(-100).(-1000)
=100000
2)30.(5-10)
=30.5-30.10
=30.5-300
=150-300
=(-150)
3) 43.(53-81)+53.(81-43)
=43.53-43.81+53.81-53.43
=(43.53-53.43)+(43.81-53.81)
=0+81.(43-53)
=(-810)
4) Mk chưa biết làm nha
1) (-25).8.(-4).(-125)
= [ (-25) . (-4) ] . [ 8 . (-125) ]
= 100 . (-1000)
= -100 000
2) 30.(-5-10)
= 30 . (-15)
= -450
3) 43.(53-81)+53.(81-43)
= 43 . 53 - 43 . 81 + 53 . 81 - 53.43
= -43 . 81 + 53 . 81
= 81 . ( -43 + 53)
= 81 . 10
= 810
4) (-6)².(-17)+23.(-36)-72.30
= 36 . (-17) + 23 . (-36) - 72. 30
= (-36) . 17 + 23 . (-36) - 72 . 30
= (-36) . ( 17 + 23 ) - 72 . 30
= (-36) . 40 - 72.30
= (-1440 )- 2160
= -3600
# HOK TỐT #
1) (-25).8.(-4).(-125)
=[-25.(-4)].[8.(-125)]
=100.(-1000)
=-100000
2) 30.(-5-10)
=30.(-15)
=-450
3) 43.(53-81)+53.(81-43)
=43.(-28)+53.38
=-1176+2014
=838
4) (-6)².(-17)+23.(-36)-72.30
=36.(-17)+23.(-36)-72.30
=36.(-17)+(-23).36-72.30
=36.[-17+(-23)]-72.30
=36.(-40)-72.30
=-1440-2160
=-3600
Bài 4: Tính nhanh
1/ 5 . 25 . 2 . 16 . 4 2/ 25 . 5 . 4 . 27 . 2 3/ 23 . 17 - 23 . 17 4/ 58 .75 + 58 . 50 – 58 . 25 | 5/ 125 . 98 – 125 . 46 – 52 . 25 6/ 136 . 23 + 136 . 17 – 40 . 36 7/ 5 . 23 + 35 . 41 + 64 . 65 8/ 29 . 87 – 29 . 23 + 64 . 71 |