A=3+5+7+...+49
Số số hạng là (49-3):2+1=46:3+1=24 số
Tổng là (49+3)*24/2=52*12=624
=>\(B=\dfrac{4-624}{217}=\dfrac{-620}{217}=-\dfrac{20}{7}\)
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Bài 1:Tính bằng cách hợp lý (nếu có thể)
a,16dfrac{2}{7}:left(dfrac{-3}{5}right)+28dfrac{2}{7}:dfrac{3}{5}
b,dfrac{3}{5}:left(dfrac{-1}{15}-dfrac{1}{6}right)+dfrac{3}{5}:left(dfrac{-1}{3}-1dfrac{1}{15}right)
c,left(-6,5right).5,7+5,7.left(-3.5right)
d,10.sqrt{0,01.}sqrt{ }dfrac{16}{9}+3sqrt{49}-dfrac{1}{6}sqrt{4}
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Bài 1:Tính bằng cách hợp lý (nếu có thể)
a,\(16\dfrac{2}{7}:\left(\dfrac{-3}{5}\right)+28\dfrac{2}{7}:\dfrac{3}{5}\)
b,\(\dfrac{3}{5}:\left(\dfrac{-1}{15}-\dfrac{1}{6}\right)+\dfrac{3}{5}:\left(\dfrac{-1}{3}-1\dfrac{1}{15}\right)\)
c,\(\left(-6,5\right).5,7+5,7.\left(-3.5\right)\)
d,\(10.\sqrt{0,01.}\sqrt{ }\dfrac{16}{9}+3\sqrt{49}-\dfrac{1}{6}\sqrt{4}\)
Tìm x , y , z biết :
\(\dfrac{2x}{3}=\dfrac{3y}{4}=\dfrac{4z}{5}\) và x + y + z = 49
Thuc hien phep tinh;
a/ 1dfrac{4}{23}+dfrac{5}{21}-dfrac{4}{23}+0,5+dfrac{16}{21}
b/ left(dfrac{1}{25}+dfrac{1}{5}+1right):left(dfrac{1}{25}-dfrac{1}{5}-1right)
c/ dfrac{dfrac{1}{9}-dfrac{1}{7}-dfrac{1}{11}}{dfrac{4}{9}-dfrac{4}{7}-dfrac{4}{11}}+ dfrac{0,6-dfrac{3}{25}-dfrac{3}{125}-dfrac{3}{625}}{dfrac{4}{5}-0,16-dfrac{4}{125}-dfrac{4}{625}}
d/ dfrac{2^{12}.3^5-4^6.9^2}{left(2^2.3right)^6+8^4.3^5}-dfrac{5^{10}.7^3-25^5.49^2}{left(125.7right)^3+5^9.14^3}
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Thuc hien phep tinh;
a/ \(1\dfrac{4}{23}+\dfrac{5}{21}-\dfrac{4}{23}+0,5+\dfrac{16}{21}\)
b/ \(\left(\dfrac{1}{25}+\dfrac{1}{5}+1\right):\left(\dfrac{1}{25}-\dfrac{1}{5}-1\right)\)
c/ \(\dfrac{\dfrac{1}{9}-\dfrac{1}{7}-\dfrac{1}{11}}{\dfrac{4}{9}-\dfrac{4}{7}-\dfrac{4}{11}}\)+ \(\dfrac{0,6-\dfrac{3}{25}-\dfrac{3}{125}-\dfrac{3}{625}}{\dfrac{4}{5}-0,16-\dfrac{4}{125}-\dfrac{4}{625}}\)
d/ \(\dfrac{2^{12}.3^5-4^6.9^2}{\left(2^2.3\right)^6+8^4.3^5}-\dfrac{5^{10}.7^3-25^5.49^2}{\left(125.7\right)^3+5^9.14^3}\)
3 tháng 2 2022 lúc 22:48
\(E=\dfrac{\left(13\dfrac{1}{4}-2\dfrac{5}{27}-10\dfrac{5}{6}\right).230\dfrac{1}{25}+46\dfrac{3}{4}}{\left(1\dfrac{3}{7}+\dfrac{10}{3}\right):\left(12\dfrac{1}{3}-14\dfrac{2}{7}\right)}\)
a)dfrac{5}{15}+dfrac{14}{25}-dfrac{12}{9}+dfrac{2}{7}+dfrac{11}{25}
b)left(dfrac{3}{7}-dfrac{5}{2}-dfrac{3}{5}right)-left(-dfrac{4}{7}-dfrac{3}{2}+dfrac{2}{5}right)
c)left(dfrac{2}{5}right)^2+5dfrac{1}{2}.left(4,5-2right)+dfrac{2^3}{left(-4right)}
d)left(-dfrac{1}{2}right)^2:dfrac{1}{4}-2.left(-dfrac{1}{2}right)^3
e)sqrt{16}.1dfrac{3}{4}+dfrac{1}{4}-7
f)dfrac{2^9.4^{10}}{8^8}
Đọc tiếp
a)\(\dfrac{5}{15}+\dfrac{14}{25}-\dfrac{12}{9}+\dfrac{2}{7}+\dfrac{11}{25}\)
b)\(\left(\dfrac{3}{7}-\dfrac{5}{2}-\dfrac{3}{5}\right)-\left(-\dfrac{4}{7}-\dfrac{3}{2}+\dfrac{2}{5}\right)\)
c)\(\left(\dfrac{2}{5}\right)^2+5\dfrac{1}{2}.\left(4,5-2\right)+\dfrac{2^3}{\left(-4\right)}\)
d)\(\left(-\dfrac{1}{2}\right)^2:\dfrac{1}{4}-2.\left(-\dfrac{1}{2}\right)^3\)
e)\(\sqrt{16}.1\dfrac{3}{4}+\dfrac{1}{4}-7\)
f)\(\dfrac{2^9.4^{10}}{8^8}\)
Thực hiện phép tính (bằng cách hợp lí nếu có thể)
a) \(1\dfrac{4}{23}+\dfrac{5}{21}-\dfrac{4}{23}+0,5+\dfrac{16}{21}\)
b) \(\dfrac{3}{7}.19\dfrac{1}{3}-\dfrac{3}{7}.33\dfrac{1}{3}\)
c) \(9.\left(\dfrac{1}{3}\right)^3+\dfrac{1}{3}\)
d) \(15\dfrac{1}{4}:\left(-\dfrac{5}{7}\right)-25\dfrac{1}{4}:\left(-\dfrac{5}{7}\right)\)
Tìm x, biết
a, \(\dfrac{3}{7}+\dfrac{4}{7}x=\dfrac{1}{3}\)
b, \(25-\left(5-x\right)=-7\)
c, \(\dfrac{3}{4}+\dfrac{1}{4}:x=\dfrac{2}{5}\)
d, \(2x\left(x-\dfrac{1}{7}\right)=0\)
e, \(\left|\dfrac{1}{2}x-\dfrac{3}{4}\right|-7=-3\)
thực hiện phép tính (tính hợp lí nếu có thể)
1) -0,75.dfrac{12}{-5}.4dfrac{1}{6}.left(-1right)^2
2) dfrac{11}{25}.left(-24,8right)-dfrac{11}{25}.75,2
3) left(-dfrac{3}{4}+dfrac{2}{7}right):dfrac{2}{3}+left(-dfrac{1}{4}+dfrac{5}{7}right):dfrac{2}{3}
4) left(dfrac{1}{2}-dfrac{2}{3}right)-left(dfrac{5}{3}-dfrac{3}{2}right)+left(dfrac{7}{3}-dfrac{5}{2}right)
5) left(-2right)^2+sqrt{36}-sqrt{9}+sqrt{25}
6) left(-dfrac{1}{3}right)^2.dfrac{4}{11}+dfrac{7}{11}.left(-dfrac{1}{3}right)^2
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thực hiện phép tính (tính hợp lí nếu có thể)
1) \(-0,75.\dfrac{12}{-5}.4\dfrac{1}{6}.\left(-1\right)^2\)
2) \(\dfrac{11}{25}.\left(-24,8\right)-\dfrac{11}{25}.75,2\)
3) \(\left(-\dfrac{3}{4}+\dfrac{2}{7}\right):\dfrac{2}{3}+\left(-\dfrac{1}{4}+\dfrac{5}{7}\right):\dfrac{2}{3}\)
4) \(\left(\dfrac{1}{2}-\dfrac{2}{3}\right)-\left(\dfrac{5}{3}-\dfrac{3}{2}\right)+\left(\dfrac{7}{3}-\dfrac{5}{2}\right)\)
5) \(\left(-2\right)^2+\sqrt{36}-\sqrt{9}+\sqrt{25}\)
6) \(\left(-\dfrac{1}{3}\right)^2.\dfrac{4}{11}+\dfrac{7}{11}.\left(-\dfrac{1}{3}\right)^2\)
Tính :
\(E=\dfrac{\left(13\dfrac{1}{4}-2\dfrac{5}{27}-10\dfrac{5}{6}\right).230\dfrac{1}{25}+46\dfrac{3}{4}}{\left(1\dfrac{3}{7}+\dfrac{10}{3}\right):\left(12\dfrac{1}{3}-14\dfrac{2}{7}\right)}\)