a) 10000-9500+9000-8500+8000-7500+........+ 2000-1500+1000-500
b)2005+53-54-55+56+57-58-59+60+61-62-63+64+65-66-67+68+69
tinh nhanh cach tinh
Tính giá trị biểu thức
M = 2005+(53-54-55+56)+(57-58-59+60)+(61-62-63+64)+(65-66-67+68)+69
các phép tính trong ngoặc đều bằng 0
suy ra chỉ còn 2005 +69 = 2074
Tính nhanh:
2005+53-54-55+56+57-58-59+60+61-62-63+64+65-66-67+68+69
...GIẢI CHI TIẾT...
ta có: 2005 + 53-54-55+56-57-58-59+60+61-62-63+64+65-66-67+68+69
= 2005+(53-54-55+56)+(57-58-59+60)+(61-62-63+64)+(65-66-67+68)+69
= 2005+0+0+0+0+69
= 2005+69
= 2074
2005+53-54-55+56+57-58+59+. . .+65-66-67+68+69
ta có: 2005 + 53-54-55+56-57-58-59+60+61-62-63+64+65-66-67+68+69
= 2005+(53-54-55+56)+(57-58-59+60)+(61-62-63+64)+(65-66-67+68)+69
= 2005+0+0+0+0+69
= 2005+69
= 2074
(57+58+59+60+61+62+63+64+65+66+67+68+69+70):5=bn
ai nhanh mk tick cho nhớ kb với mk nha
\(\left(57+58+59+60+61+62+63+64+65+66+67+68+69+70\right):5\)
\(=\left[\left(70+57\right).14:2\right]:5\)
\(=\left[127.14:2\right]:5\)
\(=1778:2:5\)
\(=889:5\)
\(=\frac{889}{5}\)
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+51+52+53+54+56+57+58+59+60+61+62+63+64+65+66+67+68+69+70=?
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?
Tính nhanh:(chỉ có 5 phút để trả lời)
42 + 43 + 44 + 45 - 32 - 33 - 34 - 35
(64+ 65+ 66+ 67+ 68) - (54 + 55 + 56 + 57 + 58)
42 + 43 + 44 + 45 - 32 - 33 - 34 - 35
= (42 - 32)+(43 - 33)+(44 - 34)+(45 - 35)
= 10+10+10+10
= 40
(64+65+66+67+68) - (54+55+56+57+58)
= 64+65+66+67+68 - 54-55-56-57-58
= (64 - 54)+(65 - 55) +(66 - 56) + (67- 57) + (68 -58)
= 10+10+10+10+10
= 50
câu 1 40
câu 2 50
nha
Tính nhanh
a) (45-63+18) x (1+2+3+4+5+6+7+8+9)
b) 60-61+62-63+64-65+66-67+68-69+70
a. (45-63+18) x (1+2+3+4+5+6+7+8+9)
= 0 x (1+2+3+4+5+6+7+8+9) = 0
b. 60-61+62-63+64-65+66-67+68-69+70
= 60 + (-61-69)+(62+68)+(-63-67)+(64+66)-65+70
= 60 + (-130)+130+(-130)+130-65-70
= 60 + (-130+130) + (-130+130)-65+70
= 60 - 65 + 70 = 65