tính nhanh : \(\frac{2014\cdot2015+1014}{2014\cdot2016-1000}=?\)
\(\frac{45\cdot16-17}{45\cdot15+28}\) các bạn đề là tính nhanh nhé
Ví dụ: \(\frac{2016\cdot2015-5}{2014\cdot2016+2011}=\frac{2016\cdot\left(2014+1\right)-5}{2014\cdot2016+2011}=\frac{2016\cdot2014+2016\cdot1-5}{2014\cdot2016-2011}=\frac{2016\cdot2014+2011}{2014\cdot2016+2011}=1\)
\(\left(2013\cdot2014+2014\cdot2015+2015\cdot2016\right)\cdot\left(1+\frac{1}{3}-1\frac{1}{3}\right)\)
\(\left(2013.2014+2014.2015+2015.2016\right)\left(1+\frac{1}{3}-1\frac{1}{3}\right)\)
\(=\left(2013.2014+2014.2015+2015.2016\right)\left(\frac{4}{3}-\frac{4}{3}\right)\)
\(=\left(2013.2014+2014.2015+2015.2016\right).0\)
\(=0\)
Tính nhanh :
a) \(\frac{2015\cdot2017-1}{2014+2015\cdot2016}\)
b) \(\frac{1}{1\cdot5}+\frac{1}{5\cdot9}+...+\frac{1}{2011\cdot2015}\)
c)\(\frac{12}{35}+\frac{1212}{3535}+\frac{121212}{353535}+\frac{12121212}{35353535}\)
a,\(\frac{2015.2016+2015-1}{2014+2015.2016}=\frac{2015.2016+2014}{2014+2015.2016}=1\)\(1\)
b,\(=1-\frac{1}{5}+\frac{1}{5}...-\frac{1}{2011}+\frac{1}{2011}-\frac{1}{2015}=1-\frac{1}{2015}=\frac{2014}{2015}\)
c,\(=\frac{12}{35}+\frac{12}{35}+\frac{12}{35}+\frac{12}{35}=\frac{12}{35}.4=\frac{48}{35}\)
b>=1-1/5+1/5-1/9+...+1/2011-1/2015
=1-1/2015
=2014/2015
c>=12/35+12/35+12/35+12/35
=12/35x4
=48/35
tính nhanh : \(\frac{2014\times150+1000}{151\times2014-1014}\)
tính nhanh
2014 . 150 + 1000 / 151 . 2014 -1014
/ có nghĩa là phần
dấu chấm là dấu nhân
\(\frac{2014.150+1000}{151.2014-1014}\)= \(\frac{150+1000}{\left(150+1\right).1014}\)
= \(\frac{1000}{1014}\)= \(\frac{500}{507}\)
nhớ ủng hộ mik nha
a. \(A=0.1+0.2+.......+0.19\)
b. \(B=\left(2017\cdot2016+2014\cdot2015\right)\cdot\left(1+\frac{1}{2}:1\frac{1}{2}+1\frac{1}{3}\right)\)
a. ta có (0.1+0.19)+(0.2+0.18)......+0.10
A=0.20+0.20++0.20+0.20+0.20+0.20+0.20+0.20+0.20+0.10
A=1.90
câu b mình pó tay
a ) \(A=0,1+0,2+...+0,19\)
\(A=\left(0,1+0,2+...+0,9\right)+\left(0,10+0,11+...+0,19\right)\)
\(A=0,1\times\left(1+2+...+9\right)+0,1\times\left(1+1,1+...+1,9\right)\)
\(A=0,1\times45+0,1\times14,5\)
\(A=0,1\times\left(45+14,5\right)\)
\(A=0,1\times59,5\)
\(A=5,95\)
b ) \(B=\left(2017\times2016+2014\times2015\right)\times\left(1+\frac{1}{2}\div1\frac{1}{2}+1\frac{1}{3}\right)\)
\(B=\left(2017\times2016+2014\times2015\right)\times\left(1+\frac{1}{2}\div\frac{3}{2}+\frac{4}{3}\right)\)
\(B=\left(2017\times2016+2014\times2015\right)\times\left(1+\frac{2}{6}+\frac{4}{3}\right)\)
\(B=\left(2017\times2016+2014\times2015\right)\times\frac{8}{3}\)
Tính
\(A=1\cdot2\cdot3+2\cdot3\cdot4+3\cdot4\cdot5+...+2014\cdot2015\cdot2016\)
\(A=1.2.3+2.3.4+3.4.5+....+2014.2015.2016\)
\(4A=1.2.3.4+2.3.4.\left(5-1\right)+3.4.5.\left(6-2\right)+....+2014.2015.2016.\left(2017-2013\right)\)\(4A=1.2.3.4+2.3.4.5-1.2.3.4+3.4.5.6-2.3.4.5+...+2014.2015.2016.2017-2013.2014.2015.2016\)\(4A=2014.2015.2016.2017\)
\(A=\dfrac{2014.2015.2016.2017}{4}=4215446423280\)
tinh nhanh
2014*150+1000
151*2014-1014
xét mẫu số : 151 x 2014 - 1014
= 2014x(150+1) - 1014
= 2014 x 150 + 2014 - 1014
= 2014 x 150 + 1000
vậy phân số sẽ trờ thành : 2014 x 150 + 1000 / 2014 x 150 + 1000 =1
\(\frac{2014\cdot150+1000}{151\cdot2014-1014}=\frac{2014\cdot150+1000}{\left(150+1\right)\cdot2014-1014}\)
\(=\) \(\frac{2014\cdot150+1000}{2014\cdot150+2014\cdot1-1014}=\frac{2014\cdot150+1000}{2014\cdot150+2014=1014}\)
\(=\frac{2014\cdot150+1000}{2014\cdot150+1000}=1\)
\(2014.150+1000\)
\(\left(150+1\right)\)\(.2014-1014\)
\(=2014.150+1000\)
\(150.2014+2014-1014\)
\(=2014.150+1000\)
\(150.2014+1000\)
\(=1\)
\(\frac{2014\cdot2015-1}{2013\cdot2015+2014}\)