Tính:
a) − 8 18 + − 15 27
b) 16 20 − 15 25
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2:
a: \(2^2\cdot3-4=4\cdot3-4=12-4=8\)
b: \(16-2^3\cdot2=16-2^4=16-16=0\)
c: \(4^2-4\cdot2=16-8=8\)
d: \(3^3-2\cdot3^2=27-2\cdot9=27-18=9\)
e: \(7^2-9\cdot2^2=49-9\cdot4=49-36=13\)
f: \(2^2\cdot3+4^2=4\cdot3+16=12+16=28\)
Bài 1:
a: \(13+21\cdot5-\left(198:11-8\right)\)
\(=13+105-18+8\)
=21+87
=108
b: \(272:16-5+4\cdot\left(30-5-255:17\right)\)
\(=17-5+4\cdot\left(30-5-15\right)\)
\(=12+4\cdot10=12+40=52\)
c: \(15\cdot24-14\cdot5\cdot\left(145:5-27\right)\)
\(=360-70\left(29-27\right)\)
=360-140
=220
d: \(18\cdot3-18\cdot2+3\cdot\left(\dfrac{51}{17}\right)\)
\(=18\left(3-2\right)+3\cdot3\)
=18+9
=27
e: \(64+115+36-25\cdot8\cdot6\cdot2^2\cdot3+4^2\)
\(=100+115-200\cdot6\cdot4\cdot3+16\)
\(=231-14400=-14169\)
f: \(15\cdot8-\left(17-30+83\right)-144:6\)
\(=120-24-\left(100-30\right)\)
=96-70
=26
a) \(\dfrac{2}{5}-\dfrac{3}{15}\)
\(=\dfrac{2}{5}-\dfrac{3:3}{15:3}\)
\(=\dfrac{2}{5}-\dfrac{1}{5}\)
\(=\dfrac{1}{5}\)
b) \(\dfrac{9}{27}-\dfrac{2}{9}\)
\(=\dfrac{9:3}{27:3}-\dfrac{2}{9}\)
\(=\dfrac{3}{9}-\dfrac{2}{9}\)
\(=\dfrac{1}{9}\)
c) \(\dfrac{18}{24}-\dfrac{4}{8}\)
\(=\dfrac{18:6}{24:6}-\dfrac{4:2}{8:2}\)
\(=\dfrac{3}{4}-\dfrac{2}{4}\)
\(=\dfrac{1}{4}\)
d) \(\dfrac{6}{16}-\dfrac{10}{64}\)
\(=\dfrac{6\times2}{16\times2}-\dfrac{10:2}{64:2}\)
\(=\dfrac{12}{32}-\dfrac{5}{32}\)
\(=\dfrac{7}{32}\)
15 - (-15 + 2) = 15 + 13 = 28
(-14) - (17 - 8) = -14 - 9 = -23
15 - (21- 7) = 15 - 14 = 1
34 + (-15) - 17 = 19 - 17 = 2
(-34) + (-12) + 18 = -46 + 18 = -28
27 - 15 - 19 = 12 - 19 = -7
34 - (-15) + 8 = 49 + 8 = 57
-37 + 13 - 25 = -24 - 25 = -49
40 - 17 + (-25) = 23 + (-25) = -2
16 + (-15) - 18 = 1 - 18 = -17
15 - 14 - 13 = 1 - 13 = -12
-27 + 15 - 17 = -12 - 17 = -29
34 - 71 = -37
28 - 125 = -97
13 + (-27) = -14
14 - (-34) = 48
28 - (-16) = 44
-15 - 8 = -23
-27 - 34 = -61
-25 - (-18) = -7
46 - 25 - (-25) = 21 + 25 = 46
-37 - (-24) = -13
46 - (-15) = 61
-26 - 6 + 7 = -32 + 7 = -25
@linhcute
\(\frac{5}{15}+\frac{3}{15}+\frac{4}{20}+\frac{18}{27}+\frac{12}{16}+\frac{20}{25}\\ =\frac{1}{3}+\frac{1}{5}+\frac{1}{5}+\frac{2}{3}+\frac{3}{4}+\frac{4}{5}\\ \)
\(=\left(\frac{1}{3}+\frac{2}{3}\right)+\left(\frac{1}{5}+\frac{1}{5}+\frac{4}{5}\right)+\frac{3}{4}\\ =1+\frac{5}{6}+\frac{3}{4}=2\frac{7}{12}=\frac{31}{12}\)
#Châu's ngốc
a) \(27^{64}:81^{20}=3^{192}:3^{80}=3^{112}\)
b) \(\left(\dfrac{1}{8}\right)^{20}:\left(\dfrac{1}{16}\right)^9=\left(\dfrac{1}{2}\right)^{60}:\left(\dfrac{1}{2}\right)^{36}=\left(\dfrac{1}{2}\right)^{24}\)
c) \(\dfrac{1}{3}:\dfrac{1}{5}-\dfrac{1}{6}=\dfrac{5}{3}-\dfrac{1}{6}=\dfrac{10}{6}-\dfrac{1}{6}=\dfrac{9}{6}=\dfrac{3}{2}\)
\(\dfrac{5}{15}+\dfrac{3}{12}+\dfrac{2}{10}+\dfrac{18}{27}+\dfrac{12}{16}+\dfrac{20}{25}\)
\(=\dfrac{1}{3}+\dfrac{2}{3}+\dfrac{1}{4}+\dfrac{3}{4}+\dfrac{1}{5}+\dfrac{4}{5}\)
=3
\(\frac{48x700-24x45x20}{45-40+35-30+25-20+15-10}\)
\(=\frac{24x2x700-24x45x20}{5+5+5+5}\)
\(=\frac{24x1400-24x900}{20}\)
\(=\frac{24x\left(1400-900\right)}{20}\)
\(=\frac{24x500}{20}\)
\(=\frac{12000}{20}\)
\(=600\)
k nha
\(\frac{27x45+27x55}{2+4+6+...+16+18}\)
\(=\frac{27x\left(45+55\right)}{2+4+6+...+16+18}\)
\(=\frac{27x100}{2+4+6+...+16+18}\)
\(=\frac{2700}{\left(2+18\right)x9:2}\)
\(=\frac{2700}{90}\)
\(=30\)
k nha
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
=(1 + 19) + (2 +18) + (3 + 27) + (4 + 26) + (5 + 25) + (6 + 24) + (7 + 23) + (8 + 22) + (9 + 21) + (10 + 20) + (11 +19) + (12 + 18) + (13 + 17) + (14 + 16)
=20 + 20 + 30 + 30 + 30 + 30 + 30 + 30 + 30 + 30 + 30 + 30 + 30 + 15
=40 + 330 + 15
=381
a) − 8 18 + − 15 27 = − 4 9 + − 5 9 = − 1
b) 16 20 − 15 25 = 4 5 − 3 5 = 1 5