Tính bằng cách thuận tiện nhất :
\(\dfrac{5\times107+5-5\times8}{5}\)
Tính bằng cách thuận tiện nhất:
\(\dfrac{2}{5}\) *\(\dfrac{4}{7}\)+\(\dfrac{3}{5}\)*\(\dfrac{4}{7}\)
\(\dfrac{4}{7}x\left(\dfrac{2}{5}+\dfrac{3}{5}\right)=\dfrac{4}{7}x1=\dfrac{4}{7}\)
2/5 x 4/7 + 3/5 x 4/7
= (2/5 + 3/5 ) x 4/7
= 1 x 4/7
= 4/7
2/5 *4/7+3/5*4/7
=( 2/5 + 3/5 ) *4/7
= 1 * 4/7
= 4/7
tính bằng cách thuận tiện nhất
\(\left(\dfrac{4}{5}+\dfrac{5}{4}\right)\)x\(\dfrac{3}{4}\)
\(=\dfrac{16+25}{20}\cdot\dfrac{3}{4}=\dfrac{41}{20}\cdot\dfrac{3}{4}=\dfrac{123}{80}\)
Tính bằng cách thuận tiện nhất :
\(\dfrac{3}{4}\)+\(\dfrac{2}{5}\)+\(\dfrac{3}{12}\)
`3/4+2/5+3/12`
`=3/4+3/12+2/5`
`=9/12+3/12+2/5`
`=12/12+2/5`
`=1+2/5`
`=7/5`
Tính bằng cách thuận tiện nhất
\(\dfrac{2}{3}\times\dfrac{3}{4}\times\dfrac{4}{5}\)
\(\dfrac{2}{3}\times\dfrac{3}{4}\times\dfrac{4}{5}\) \(=\dfrac{2\times3\times4}{3\times4\times5}\) \(=\) \(\dfrac{2}{5}\)
\(\dfrac{2}{3}x\dfrac{3}{4}x\dfrac{4}{5}=\dfrac{2}{5}\)
\(\dfrac{2}{3}\)x\(\dfrac{3}{5}\)=\(\dfrac{2}{5}\)
Tính bằng cách thuận tiện nhất :
\(\dfrac{42\times45}{5\times7}\)
\(\dfrac{54\times56}{7\times9}\)
\(\dfrac{42x45}{5x7}=\dfrac{7x6x5x9}{5x7}=\dfrac{54}{1}=54\)
\(\dfrac{54x56}{7x9}=\dfrac{6x9x7x8}{7x9}=\dfrac{48}{1}=48\)
`(42 xx45)/(5xx7) =( 6xx7xx9xx5)/(5xx7) = 6 xx9 = 54`
`(54xx56)/(7xx9) = (9xx6xx7xx8)/(7xx9) = 6xx8 = 48`
tính bằng cách thuận tiện nhất a, \(\dfrac{5}{13}\)x\(\dfrac{4}{15}\)x13= b, (\(\dfrac{3}{7}\)+\(\dfrac{5}{2}\))x\(\dfrac{7}{5}\)= c, \(\dfrac{1}{5}\)x\(\dfrac{11}{18}\)+\(\dfrac{11}{18}\)x\(\dfrac{3}{5}\)=
\(a,\dfrac{5}{13}\times\dfrac{4}{15}\times13=\dfrac{5\times4\times13}{13\times5\times3}=\dfrac{4}{3}\\ b,\left(\dfrac{3}{7}+\dfrac{5}{2}\right)\times\dfrac{7}{5}=\dfrac{3}{7}\times\dfrac{7}{5}+\dfrac{5}{2}\times\dfrac{7}{5}=\dfrac{3}{5}+\dfrac{7}{2}=\dfrac{6}{10}+\dfrac{35}{10}=\dfrac{41}{10}\\ c,\dfrac{1}{5}\times\dfrac{11}{18}+\dfrac{11}{18}\times\dfrac{3}{5}=\dfrac{11}{18}\times\left(\dfrac{1}{5}+\dfrac{3}{5}\right)=\dfrac{11}{18}\times\dfrac{4}{5}=\dfrac{22}{45}\)
Bài 1: Tính:
1200-\(\dfrac{31}{40}\)
Bài 2 Tính bằng cách thuận tiện nhất:
\(^{\dfrac{5}{8}x\dfrac{9}{7}+\dfrac{5}{8}x\dfrac{5}{7}}\)
(Bài 2 trình bày từng bước hộ mik nha) GẤP
1200-31/40=47969/40
câu 2 =45/56+25/56=(45+25)/56=70/56=5/4
Tính bằng cách thuận tiện nhất
\(\dfrac{17}{2}+\dfrac{3}{5}+\dfrac{3}{5}x\dfrac{1}{2}+\dfrac{3}{5}\)
ừm cái này em đầu hàng ai giải thì giải ko giải cũng đc
\(=\dfrac{17}{2}+\dfrac{3}{5}\times\left(1+\dfrac{1}{2}+1\right)=\dfrac{17}{2}+\dfrac{3}{5}\times\dfrac{5}{2}=\dfrac{17}{2}+\dfrac{15}{10}=\dfrac{17}{2}+\dfrac{3}{2}=\dfrac{17+3}{2}=\dfrac{20}{2}=10\)
\(\dfrac{17}{2}+\dfrac{3}{5}+\dfrac{3}{5}\times\dfrac{1}{2}+\dfrac{3}{5}=\dfrac{17}{2}+\dfrac{3}{5}+\dfrac{3}{10}+\dfrac{3}{5}=\dfrac{85}{10}+\dfrac{6}{10}+\dfrac{3}{10}+\dfrac{6}{10}=10\)
Tính bằng cách thuận tiện nhất:
a, \(\dfrac{3}{5}\) x \(\dfrac{6}{7}\) + \(\dfrac{3}{5}\) : 7 + \(\dfrac{6}{5}\) =
\(a,=\left(\dfrac{3}{5}+\dfrac{3}{5}+\dfrac{6}{5}\right)\times\left(\dfrac{6}{7}:7\right)=3\times\dfrac{6}{49}=\dfrac{18}{49}\)
\(\dfrac{3}{5}\times\dfrac{6}{7}+\dfrac{3}{5}:7+\dfrac{6}{5}\\ =\dfrac{3}{5}\times\dfrac{6}{7}+\dfrac{3}{5}\times\dfrac{1}{7}+\dfrac{6}{5}\\ =\dfrac{3}{5}\times\left(\dfrac{6}{7}+\dfrac{1}{7}\right)+\dfrac{6}{5}\\ =\dfrac{3}{5}+\dfrac{6}{5}=\dfrac{9}{5}\)