100-50+87-64+43-18+42-34-1
Tính:
a) 5-14+52-4+14-51+4
b)-/-13/-(-20)+13+(-20)-8
c)34-(-18)+/-5/-18+(-34)
d) -/-49/+(-42) - (-50)+43
e) 48 - (-52) + 64 + (-34)
làm rõ ràng chi tiết dùm mk nha, cảm ơn các bạn
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+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+56+57+58+59+60+61+62+63+64+65+66+67+68+69+70=?
sắp xếp các phân số sau theo thứ tự giảm dần
\(\dfrac{73}{72}\) ; \(\dfrac{43}{42}\) ; \(\dfrac{53}{52}\); \(\dfrac{65}{64}\); \(\dfrac{87}{86}\)
\(\dfrac{73}{72}=1+\dfrac{1}{72}\)
\(\dfrac{43}{42}=1+\dfrac{1}{42}\)
\(\dfrac{53}{52}=1+\dfrac{1}{52}\)
\(\dfrac{65}{64}=1+\dfrac{1}{64}\)
\(\dfrac{87}{86}=1+\dfrac{1}{86}\)
mà \(\dfrac{1}{42}>\dfrac{1}{52}>\dfrac{1}{64}>\dfrac{1}{72}>\dfrac{1}{86}\left(42< 52< 64< 72< 86\right)\)
nên \(\dfrac{43}{42}>\dfrac{53}{52}>\dfrac{65}{64}>\dfrac{73}{72}>\dfrac{87}{86}\)
Bài 2: Tính hợp lí
a) 32.(- 64) – 64.68 b) - 54.76 + 12.(- 76) – 76.(- 36) | c) 8.19 – 42.(- 19) + 38.5 d) 74.(- 41) + 41.24 | e) – 43.38 + 12.(- 43) – 50.(- 43) f) 32 – 42.(- 16) + 48.5 – (- 16) |
a: =-64(32+68)=64x100=-6400
b: =76(-54-12+36)=76x(-30)=-2380
c: =19x50+38x5=950+190=1140
Điền > < =
(87 + 3) : 3 ........ 30
25 + (42 – 11) ........ 55
100 ........ 888 : (4 + 4)
50 ........ (50 +50) : 5
(87 + 3) : 3 = 30
25 + (42 – 11) > 55
100 < 888 : (4 + 4)
50 > (50 +50) : 5
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=?
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=1275
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.
Có ai rảnh đâu mà đi ngồi cộng ngần đấy số ra.