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\(\dfrac{36}{35}=1,0\left(285714\right)\)
\(\dfrac{10}{15}=\dfrac{2}{3}=0,\left(6\right)\)
\(\dfrac{5}{11}=0,\left(45\right)\)
\(\dfrac{2}{13}=0,\left(153846\right)\)
\(\dfrac{15}{82}=0,1\left(82926\right)\)
\(\dfrac{13}{22}=0,5\left(90\right)\)
\(\dfrac{1}{60}=0,01\left(6\right)\)
\(\dfrac{5}{24}=0,208\left(3\right)\)
Câu 3:
a: Số học sinh của lớp là:
4+15+20+10+1=50 bạn
\(\%Xs=\dfrac{4}{50}=8\%\)
%Tốt=15/50=30%
%Khá=20/50=40%
%Đạt=10/50=20%
%Chưa đạt=1/50=2%
b:
`a) `
`P`(`x`)`=3x^3 -5x^2 -x^3 -6x+2`
`=2x^3 -5x^2 -6x+2`
`Q`(`x`)`=-2x^3 -7x +1 +2x^2 -x`
`=-2x^3 +2x^2 -8x+1`
`b)`
P(x) `+ `Q(x)`=(2x^3 -5x^2 -6x+2)+(-2x^3 +2x^2 -8x+1)`
`=2x^3 -5x^2 -6x+2-2x^3 +2x^2 -8x+1`
`=-3x^2 -14x+3`
P(x) `- `Q(x)`=(2x^3 -5x^2 -6x+2)-(-2x^3 +2x^2 -8x+1)`
`=2x^3 -5x^2 -6x+2+2x^3 -2x^2 +8x-1`
`=4x^3 -7x^2 +2x +1`
b: \(=\dfrac{39}{7}\cdot\dfrac{2}{9}+\dfrac{18}{7}\cdot\dfrac{-2}{9}=\dfrac{2}{9}\cdot3=\dfrac{2}{3}\)
\(b,\dfrac{1}{2}+\dfrac{13}{19}-\dfrac{4}{9}+\dfrac{6}{19}+\dfrac{5}{18}\\ =\left(\dfrac{1}{2}+\dfrac{5}{18}\right)+\left(\dfrac{13}{19}+\dfrac{6}{19}\right)-\dfrac{4}{9}\\ =\left(\dfrac{9}{18}+\dfrac{5}{18}\right)+\dfrac{19}{19}-\dfrac{4}{9}\\ =\dfrac{14}{18}+1-\dfrac{4}{9}\\ =\dfrac{7}{9}+1-\dfrac{4}{9}\\ =\left(\dfrac{7}{9}-\dfrac{4}{9}\right)+1\\ =\dfrac{3}{9}+1\\ =\dfrac{1}{3}+1\\ =\dfrac{4}{3}\)
\(c,\dfrac{-20}{23}+\dfrac{2}{3}-\dfrac{3}{23}+\dfrac{2}{5}+\dfrac{7}{15}\\ =\left(-\dfrac{20}{23}-\dfrac{3}{23}\right)+\left(\dfrac{2}{5}+\dfrac{7}{15}\right)+\dfrac{2}{3}\\ =-\dfrac{23}{23}+\left(\dfrac{6}{15}+\dfrac{7}{15}\right)+\dfrac{2}{3}\\ =-1+\dfrac{13}{15}+\dfrac{2}{3}\\ =-\dfrac{15}{15}+\dfrac{13}{15}+\dfrac{10}{15}\\ =\dfrac{8}{15}\)
\(e,\dfrac{5}{7}.\dfrac{5}{11}+\dfrac{5}{7}.\dfrac{2}{11}-\dfrac{5}{7}.\dfrac{14}{11}\\ =\dfrac{5}{7}.\left(\dfrac{5}{11}+\dfrac{2}{11}-\dfrac{14}{11}\right)\\ =\dfrac{5}{7}.\dfrac{-7}{11}\\ =-\dfrac{35}{77}\\ =-\dfrac{5}{11}\)
\(f,\dfrac{2}{11}.\dfrac{-5}{4}+\dfrac{-9}{11}.\dfrac{5}{4}+1\dfrac{3}{4}\\ =-\dfrac{2}{11}.\dfrac{5}{4}+\dfrac{-9}{11}.\dfrac{5}{4}+\dfrac{7}{4}\\=\dfrac{5}{4}.\left(-\dfrac{2}{11}+\dfrac{-9}{11}\right)+\dfrac{7}{4}\\ =\dfrac{5}{4}.1+\dfrac{7}{4}\\ =\dfrac{5}{4}+\dfrac{7}{4}\\=\dfrac{12}{4}\\ =3\)
\(h,\dfrac{7}{4}\cdot\dfrac{29}{5}-\dfrac{7}{5}\cdot\dfrac{9}{4}+3\dfrac{2}{13}\\ =\dfrac{7}{4}\cdot\dfrac{29}{5}-\dfrac{7}{4}\cdot\dfrac{9}{5}+\dfrac{41}{13}\\ =\dfrac{7}{4}\cdot\left(\dfrac{29}{5}-\dfrac{9}{5}\right)+\dfrac{41}{13}\\ =\dfrac{7}{4}\cdot\dfrac{20}{5}+\dfrac{41}{13}\\ =\dfrac{7}{4}.4+\dfrac{41}{13}\\ =\dfrac{28}{4}+\dfrac{41}{13}\\ =7+\dfrac{41}{13}\\ =\dfrac{132}{13}\)
`@` `\text {Ans}`
`\downarrow`
`8^2 \div 49^3`
`= (2^3)^2 \div (7^2)^3`
`= 2^6 \div 7^6`
`= (2 \div 7)^6`
`= (2/7)^6`