Tính cực nhanh: 4/3x4/7+4/7x4/11+4/11x4/15.
Tính nhanh: 4/3x4/7+4/7x4/11+4/11x4/15.
= 4x4/3x7+ 4x4/7x11+ 4x4/11x15 = 4x(4/3x7 + 4/7x11+4/11x15) =4x(1/3-1/7+1/7-1/11+1/11-1/15) =4x(1/3-1/15)=4x4/15= 16/15.
8/7+-6/7x4/11-4/11x5/11
\(\dfrac{8}{7}+\dfrac{-6}{7}.\dfrac{4}{11}-\dfrac{4}{11}.\dfrac{5}{11}\)
\(=\dfrac{8}{7}+\dfrac{4}{11}\left(-\dfrac{6}{7}-\dfrac{5}{11}\right)\)
\(=\dfrac{8}{7}+\dfrac{4}{11}.\dfrac{-101}{77}\)
\(=\dfrac{8}{7}+-\dfrac{404}{847}\)
\(=\dfrac{564}{847}\)
tính nhanh
4/3*7 + 4/7*11 + 4/11*15 +.......+ 644/1995
Sửa đề:
\(\frac{4}{3.7}+\frac{4}{7.11}+\frac{4}{11.15}+...+\frac{28}{1995}\)
\(=\frac{4}{3.7}+\frac{4}{7.11}+\frac{4}{11.15}+...+\frac{4}{285}\)
\(=\frac{4}{3.7}+\frac{4}{7.11}+\frac{4}{11.15}+\frac{4}{15.19}\)
\(=\frac{1}{3}-\frac{1}{7}+\frac{1}{7}-\frac{1}{11}+\frac{1}{11}-\frac{1}{15}+\frac{1}{15}-\frac{1}{19}\)
\(=\frac{1}{3}-\frac{1}{19}\)
\(=\frac{16}{57}\)
hình như @@Kamado Tajnirou @@ bạn làm sai rồi
Tính nhanh
a.38/7+(16/7-5/3)
b.29/9-(14/9+11/9)
c.(2/7+3/8+12/7+5/8 )-19/63
d.3/7x4/9+4/9x4/7_4/9
a, \(\dfrac{38}{7}\) + ( \(\dfrac{16}{7}\) - \(\dfrac{5}{3}\))
= \(\dfrac{38}{7}\) + \(\dfrac{16}{7}\) - \(\dfrac{5}{3}\)
= \(\dfrac{54}{7}\) - \(\dfrac{5}{3}\)
= \(\dfrac{162}{21}\) - \(\dfrac{35}{21}\)
= \(\dfrac{127}{21}\)
b, \(\dfrac{29}{9}\) - ( \(\dfrac{14}{9}\) + \(\dfrac{11}{9}\) )
= \(\dfrac{29-14-11}{9}\)
= \(\dfrac{4}{9}\)
c, ( \(\dfrac{2}{7}\) + \(\dfrac{3}{8}\) + \(\dfrac{12}{7}\) + \(\dfrac{5}{8}\) ) - \(\dfrac{19}{63}\)
= ( \(\dfrac{2+12}{7}\) + \(\dfrac{3+5}{8}\)) - \(\dfrac{19}{63}\)
= \(\left(1+2\right)\) - \(\dfrac{19}{63}\)
= \(3-\dfrac{19}{63}\)
= \(\dfrac{189}{63}\) - \(\dfrac{19}{63}\)
= \(\dfrac{170}{63}\)
d, \(\dfrac{3}{7}\) . \(\dfrac{4}{9}\) + \(\dfrac{4}{9}\) . \(\dfrac{4}{7}\) - \(\dfrac{4}{9}\)
= \(\dfrac{4}{9}\) . ( \(\dfrac{3}{7}\) + \(\dfrac{3}{7}\) ) - \(\dfrac{4}{9}\)
= \(\dfrac{4}{9}\) . \(1-\dfrac{4}{9}\)
= \(\dfrac{4}{9}\) - \(\dfrac{4}{9}\)
= 0
3/11x2=
6/11:3/11=
6/11:2=
2x3/11=
4x2/7=
8/7:2/7=
8/7:4=
2/7x4=
sorry vì hơi dài giúp mik với
3/11 x 2 = 6/11
6/11 : 3/11 = 2
6/11 : 2 = 3/11
2/3 x 11 = 22/3
4/2 x 7 = 14
8/7 : 2/7 = 4
8/7 : 4 = 2/7
2/7 x 4 = 8/7
Tính nhanh:
4/15 + 35/99 + 11/15 - 2/7 + 64/99 - 5/7
(4+11):15+(35+64):99+(2+5):7=15:15+99:99+7:7=1+1+1=3
`4/15+35/99+11/15-2/7+64/99-5/7`
`=(4/15+11/15)+(35/99+64/99)-(2/7+5/7)`
`=15/15+99/99-7/7`
`=1+1-1`
`=2-1`
`=1`
Tính nhanh:
4/15 + 35/99 + 11/15 - 2/7 + 64/99 - 5/7
tính nhanh phép tính sau -5/9 + 8/ 15 + -2/11 + 4/-9 + 7/15
\(\dfrac{-5}{9}+\dfrac{8}{15}+\dfrac{-2}{11}+\dfrac{4}{-9}+\dfrac{7}{15}\)
=\(\left(\dfrac{-5}{9}+\dfrac{-4}{9}\right)+\left(\dfrac{8}{15}+\dfrac{7}{15}\right)-\dfrac{2}{11}\)
=\(-1+1-\dfrac{2}{11}=\dfrac{-2}{11}\)
\(=\left(\dfrac{-5}{9}+\dfrac{-4}{9}\right)+\left(\dfrac{8}{15}+\dfrac{7}{15}\right)+\dfrac{-2}{11}\\ =-1+1+\dfrac{-2}{11}\\ =0+\dfrac{-2}{11}=\dfrac{-2}{11}\)
\(\dfrac{-5}{9}+\dfrac{8}{15}+\dfrac{-2}{11}+\dfrac{4}{-9}+\dfrac{7}{15}\)
\(=\left(\dfrac{-5}{9}+\dfrac{-4}{9}\right)+\left(\dfrac{8}{15}+\dfrac{7}{15}\right)+\dfrac{-2}{11}\)
\(=\dfrac{-9}{9}+\dfrac{15}{15}+\dfrac{-2}{11}\)
\(=\left(-1\right)+1-\dfrac{-2}{11}\)
\(=0+\dfrac{-2}{11}\)
\(=\) \(\dfrac{-2}{11}\)
Bài 1
a)5x7 phần 15 b)8:16 phần 23 c)8 phần 15 :5
d)15 phần 19 x3
Bài 2 :
3x4/9+2/3-7/18
7/10x2/3-1/4
9/8-7/8:5/6
2/3+1/2:3/2-11/24
Bài 3 Một hình bình hành có chiều cao 3/5m độ dài đáy gập 2 lần chiều cao,cạnh bên là 4/5m tính chu vi và diện tích của hình bình hành đó.