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Câu 3:
Chiều rộng là 90x3/5=54(m)
Chu vi là (90+54)x2=288(m)
Câu 4:
Chiều rộng là 60x3/5=36(m)
Chu vi là (60+36)x2=192(m)
Diện tích là 60x36=2160(m2)
1.a \(\dfrac{17}{12}\)
b.\(\dfrac{3}{16}\)
c.\(\dfrac{5}{14}\)
d.\(2\)
2.Cr:
\(145\times\dfrac{2}{5}=58\left(m\right)\)
C:
\(\left(145+58\right)\times2=261\left(m\right)\)
1
a) \(\dfrac{5}{6}+\dfrac{7}{12}=\dfrac{10}{12}+\dfrac{7}{12}=\dfrac{17}{12}\)
b) \(\dfrac{9}{16}-\dfrac{3}{8}=\dfrac{9}{16}-\dfrac{6}{16}=\dfrac{3}{16}\)
c) \(\dfrac{4}{7}\times\dfrac{5}{8}=\dfrac{20}{56}=\dfrac{5}{14}\)
d) \(\dfrac{11}{10}+\dfrac{3}{5}\div\dfrac{2}{3}=\dfrac{11}{10}+\dfrac{9}{10}=\dfrac{21}{10}\)
2
Chiều rộng mảnh đất là :
\(145\times\dfrac{2}{5}=58\left(m\right)\)
Chu vi mảnh đất là :
\(\left(145+58\right)\times2=406\left(m\right)\)
Diện tích mảnh đất là :
\(145\times58=8410\left(m^2\right)\)
Đ/s : Chu vi :\(406m\)
Diện tích : \(8410m^2\)
3
Phân số chỉ phần của mỗi bạn là :
\(3:5=\dfrac{3}{5}\) \(\left(\text{phần}\right)\)
Đs : \(\dfrac{3}{5}\text{phần}\)
a, \(\left(4\dfrac{1}{9}+3\dfrac{1}{4}\right).2\dfrac{1}{4}+2\dfrac{3}{4}\)
\(=\left(\dfrac{37}{9}+\dfrac{13}{4}\right).\dfrac{9}{4}+\dfrac{11}{4}\)
\(=\dfrac{265}{36}.\dfrac{9}{4}+\dfrac{11}{4}\)
\(=\dfrac{265}{16}+\dfrac{11}{4}\)
\(=\dfrac{309}{16}\)
b, \(\dfrac{9}{23}.\dfrac{5}{8}+\dfrac{9}{23}.\dfrac{3}{8}-\dfrac{9}{23}\)
\(=\dfrac{45}{184}+\dfrac{27}{184}-\dfrac{9}{23}\)
\(=\dfrac{9}{23}-\dfrac{9}{23}\)
\(=\dfrac{1}{1}\)
c, \(1+\left(\dfrac{9}{10}-\dfrac{4}{5}\right)\div3\dfrac{1}{6}\)
\(=1+\left(\dfrac{9}{10}-\dfrac{4}{5}\right)\div\dfrac{19}{6}\)
\(=1+\dfrac{1}{10}\div\dfrac{19}{6}\)
\(=1+\dfrac{3}{95}\)
\(=1\dfrac{3}{95}\)
d, ???
`a)1 4/23 + ( 5/21-4/23)+16/21-1/2`
`=27/23+5/21-4/23+16/21-1/2`
`=(27/23-4/23)+(5/21+16/21)-1/2`
`=23/23+21/21-1/2`
`=1+1-1/2`
`=2-1/2`
`=4/2-1/2`
`=3/2`
___
`b)75%-(5/2+5/3)+(-1/2)^3`
`=3/4-5/2+5/3+(-1/8)`
`=(3/4-5/2-1/8)+5/3`
`=(6/8-20/8-1/8)+5/3`
`=-15/8+5/3`
`=-45/24+40/24`
`=-5/24`
___
`c)-3/4(-55/9).8/11`
`=-3/4.(-40/9)`
`=-10/3`
__
`d)-3/8 . 6/13 + 7/13 . (-3/8) + 1 3/8`
`= -3/8 . (6/13 + 7/13) + 11/8`
`= -3/8 . 13/13 + 11/8`
`= -3/8 .1 + 11/8`
`= -3/8 + 11/8`
`= 8/8`
`=1`
Giải:
a) \(\left(9\dfrac{4}{9}+5\dfrac{2}{3}\right)-5\dfrac{1}{2}\)
\(=\left(\dfrac{85}{9}+\dfrac{17}{3}\right)-\dfrac{11}{2}\)
\(=\dfrac{136}{9}-\dfrac{11}{2}\)
\(=\dfrac{173}{18}\)
b) \(\dfrac{13}{9}.\dfrac{15}{4}-\dfrac{13}{9}.\dfrac{7}{4}-\dfrac{13}{9}.\dfrac{5}{4}\)
\(=\dfrac{13}{9}.\left(\dfrac{15}{4}-\dfrac{7}{4}-\dfrac{5}{4}\right)\)
\(=\dfrac{13}{9}.\dfrac{3}{4}\)
\(=\dfrac{13}{12}\)
c) \(\dfrac{2}{3}+\dfrac{5}{8}-\dfrac{-1}{3}+0,375\)
\(=\left(\dfrac{2}{3}-\dfrac{-1}{3}\right)+\left(\dfrac{5}{8}+\dfrac{3}{8}\right)\)
\(=1+1\)
\(=2\)
d) \(75\%-3\dfrac{1}{2}+1,5:\dfrac{10}{7}\)
\(=\dfrac{3}{4}+\dfrac{7}{2}+\dfrac{3}{2}:\dfrac{10}{7}\)
\(=\dfrac{3}{4}+\dfrac{7}{2}+\dfrac{21}{20}\)
\(=\dfrac{53}{10}\)
e) \(1\dfrac{13}{15}.\left(0,5\right)^2.3+\left(\dfrac{8}{15}-1\dfrac{19}{60}\right):1\dfrac{23}{24}\)
\(=\dfrac{28}{15}.\dfrac{1}{4}.3+\left(\dfrac{8}{15}-\dfrac{79}{60}\right):\dfrac{47}{24}\)
\(=\dfrac{7}{5}+\dfrac{-47}{60}:\dfrac{47}{24}\)
\(=\dfrac{7}{5}+\dfrac{-2}{5}\)
\(=1\)
a\(\frac{2}{3}-\frac{3}{8}=\frac{7}{24}\) , b giống a , c\(\frac{4}{5}x3=\frac{12}{5}\)
2 , x-\(\frac{3}{4}=\frac{1}{2}\)
x =\(\frac{1}{2}+\frac{3}{4}\)
x =\(\frac{5}{4}\)Vậy x =\(\frac{5}{4}\)
3 .
bài giải
chiều cao mảnh đất là
42 x 2/3 = 28 ( m2 )
diện h mảnh đất là
42 x 28 = 1176 ( m2 )
đáp số 1176 m2