2 [ 3 - 9 (-3) +2(5-7) ] - 18 : (-3)2
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\(\dfrac{7}{4}.\dfrac{29}{5}-\dfrac{7}{5}.\dfrac{9}{4}+3\dfrac{2}{15}\) (đổi hỗn số ra phân số)
\(=\) \(\dfrac{7}{4}.\dfrac{29}{5}-\dfrac{7}{5}.\dfrac{9}{4}+\dfrac{47}{15}\) (nhân, chia trước cộng, trừ sau lấy \(\dfrac{7}{4}.\dfrac{29}{5}\)và lấy \(\dfrac{7}{5}.\dfrac{9}{4}\) ra kết quả rồi \(+\dfrac{47}{15}\))
\(=\dfrac{203}{20}-\dfrac{63}{20}+\dfrac{47}{15}\) (cộng, trừ thì cộng, trừ từ trái sang phải)
\(=7+\dfrac{47}{15}=\dfrac{7}{1}+\dfrac{47}{15}\)
\(=\dfrac{105}{15}+\dfrac{47}{15}\)
\(=\dfrac{152}{15}\)
NHỮNG CHỮ IN ĐẬM BẠN KHÔNG CẦN GHI
\(\dfrac{2}{3}+\dfrac{7}{5}-\dfrac{3}{5}=\dfrac{2}{3}+\dfrac{7-3}{5}=\dfrac{2}{3}+\dfrac{4}{5}=\dfrac{10+12}{15}=\dfrac{22}{15}\)
\(\dfrac{13}{6}+\dfrac{5}{3}-2=\dfrac{13+10}{6}-2=\dfrac{23}{6}-2=\dfrac{23-12}{6}=\dfrac{11}{6}\)
`@` `\text {Ans}`
`\downarrow`
\(\left(x-\dfrac{1}{5}\right)^2+1=3,5\div7\%\)
`=> (x-1/5)^2 + 1 = 3,5 \div 0,07`
`=> (x-1/5)^2 +1=50`
`=> (x-1/5)^2 = 49`
`=> (x-1/5)^2 = (+-7)^2`
`=>`\(\left[{}\begin{matrix}x-\dfrac{1}{5}=7\\x-\dfrac{1}{5}=-7\end{matrix}\right.\)
`=>`\(\left[{}\begin{matrix}x=7+\dfrac{1}{5}\\x=-7+\dfrac{1}{5}\end{matrix}\right.\)
`=>`\(\left[{}\begin{matrix}x=\dfrac{36}{5}\\x=-\dfrac{34}{5}\end{matrix}\right.\)
Vậy, `x={36/5; -34/5}.`
1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 + 11 + 12 + 13 + 14 + 15 + 16 + 17+18 = 171 nhé
1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 + 11 + 12 + 13 + 14 + 15 + 16 + 17+18. = 171
a)
`9/2-3`
`=9/2-6/2`
`=3/2`
b)
`8/5xx25/12`
`=10/3`
c)
`4:3/7`
`=4xx7/3`
`=28/3`
a: =-5/9-4/9+8/15+7/15-2/11=-2/11
b: =10/17+7/17-5/13-8/13+11/25
=11/25
c: =(9/12-2/12)*3/2=7/12*3/2=21/24=7/8
d: =(31/10-25/10)*3-2
=3/5*3-2
=9/5-2
=-1/5
\(\dfrac{2}{1.3}+\dfrac{2}{3.5}+\dfrac{2}{5.7}+\dfrac{2}{7.9}+\dfrac{2}{9.11}\\ =1-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{9}+\dfrac{1}{9}-\dfrac{1}{11}\\ =1-\dfrac{1}{11}=\dfrac{10}{11}\)
\(\dfrac{2}{1\cdot3}+\dfrac{2}{3\cdot5}+\dfrac{2}{5\cdot7}+\dfrac{2}{7\cdot9}+\dfrac{2}{9\cdot11}\\ =1-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{9}+\dfrac{1}{9}-\dfrac{1}{11}\\ =1-\dfrac{1}{11}\\ =\dfrac{10}{11}\)
\(2\left[3-9\cdot\left(-3\right)+2\left(5-7\right)\right]-18:\left(-3\right)^2\)
\(=2\left[3+27+2\cdot\left(-2\right)\right]-18:9\)
\(=2\left[30-4\right]-2\)
\(=2\cdot26-2=50\)
=2.(3-9.-3 +2.-2)-18:(-3)2
=2.(3--27+-4)-18:-9
=2.(30+-4) -18:-9
=2.26-18:-9
=52--2
=54