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A=\(\frac{1}{2}.\frac{2}{3}.\frac{3}{4}...\frac{2014}{2015}.\frac{2015}{2016}\)
A=\(\frac{1.2.3.4...2015}{2.3.4...2016}=\frac{1}{2016}\)
Hok tốt
A = \(\left(1-\frac{1}{2}\right).\left(1-\frac{1}{3}\right).\left(1-\frac{1}{4}\right)...\left(1-\frac{1}{2015}\right).\left(1-\frac{1}{2016}\right)\)
= \(\frac{1}{2}.\frac{2}{3}.\frac{3}{4}...\frac{2014}{2015}.\frac{2015}{2016}\)
= \(\frac{1}{2016}\)
Vậy ...
Tính nhanh :
\(\left(1999+313\right)-1999\)
\(=\left(1999-1999\right)+313\)
\(=0+313\)
=\(=313\)
11: \(27+12+\left(-17\right)+\left(-12\right)\)
\(=\left(27-17\right)+\left(12-12\right)\)
=10+0
=10
12: \(-564-\left(324-564-224\right)\)
\(=-564-\left(-564+100\right)\)
\(=-564+564-100=-100\)
13: \(2^3\cdot3^2-7^2-2022^0\)
\(=8\cdot9-49-1\)
=72-50
=22
14: \(236\cdot145+236\cdot856-236\)
\(=236\cdot145+236\cdot856-236\cdot1\)
\(=236\left(145+856-1\right)\)
\(=236\cdot1000=236000\)
15: \(-\left(-357\right)+27+\left(-357\right)+\left(-32\right)\)
\(=357+27-357-32\)
=27-32
=-5
16: \(275\cdot48+22\cdot275+175\left(-70\right)\)
\(=275\left(48+22\right)-175\cdot70\)
\(=275\cdot70-175\cdot70\)
\(=70\left(275-175\right)=70\cdot100=7000\)
17: \(\dfrac{\left(23\cdot36-17\cdot36\right)}{36}\)
\(=\dfrac{36\left(23-17\right)}{36}\)
=23-17
=6
18: \(3\cdot5^3-27:3^2+5^3\cdot4-18:3^2\)
\(=3\cdot5^3+4\cdot5^3-27:9-18:9\)
\(=5^3\left(3+4\right)-3-2\)
\(=125\cdot7-5=875-5=870\)
19: \(-87+\left(-12\right)-\left(-487\right)+512\)
\(=-87-12+487+512\)
\(=\left(487-87\right)+\left(512-12\right)\)
=400+500
=900
20: \(25\cdot57+75+33\cdot25+75\cdot89\)
\(=25\cdot57+25\cdot33+75+75\cdot89\)
\(=25\left(57+33\right)+75\left(1+89\right)\)
\(=25\cdot100+100\cdot75\)
\(=100\left(25+75\right)=100\cdot100=10000\)
Mik ra kết quả như thế này nè:
3.37=111.
thay x : 37*3=111
k mình mình k lại nhaMagic Super Power
thanks nhiều