\(=\dfrac{7}{12}\cdot\left(25\dfrac{3}{5}-31\dfrac{3}{5}\right)=\dfrac{7}{12}\left(-6\right)=-\dfrac{7}{2}\)
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Chương I : Số hữu tỉ. Số thực
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Tính giá trị biểu thức :
A=\(\left[\dfrac{1\dfrac{11}{31}.4\dfrac{3}{7}-\left(15-6\dfrac{1}{3}.\dfrac{2}{19}\right)}{4\dfrac{5}{6}+\dfrac{1}{6}\left(12-5\dfrac{1}{3}\right)}\right].\dfrac{31}{50}\)
1)Tính giá trị biểu thức:
dfrac{left(13dfrac{1}{4}-2dfrac{5}{27}-10dfrac{5}{6}right).230dfrac{1}{25}+46dfrac{3}{4}}{left(1dfrac{3}{7}+dfrac{10}{3}right):left(12dfrac{1}{3}-14dfrac{2}{7}right)}
2)Tìm x biết:
a) 42+dfrac{3}{7}.left|3x-1right|12
b) left|2x-1right|left|x+2right|
c) 2.3^x.3^218 với xin N
Đọc tiếp
1)Tính giá trị biểu thức:
\(\dfrac{\left(13\dfrac{1}{4}-2\dfrac{5}{27}-10\dfrac{5}{6}\right).230\dfrac{1}{25}+46\dfrac{3}{4}}{\left(1\dfrac{3}{7}+\dfrac{10}{3}\right):\left(12\dfrac{1}{3}-14\dfrac{2}{7}\right)}\)
2)Tìm x biết:
a) \(42+\dfrac{3}{7}.\left|3x-1\right|=12\)
b) \(\left|2x-1\right|=\left|x+2\right|\)
c) \(2.3^x.3^2=18\) với \(x\in N\)
Tìm x, y, z biết
\(\dfrac{x}{3}=\dfrac{y}{5};\dfrac{z}{7}=\dfrac{y}{3}\) và x - y = -12
\(\dfrac{a}{b}=\dfrac{5}{7}\)va x+y =72
\(\dfrac{a}{6}=\dfrac{b}{4}=\dfrac{c}{3}\)va a+b-c=21
\(\dfrac{12}{x}=\dfrac{3}{y}\)va x-y = 36
\(\dfrac{a}{2}=\dfrac{b}{5}=\dfrac{c}{7}\)va a+b-c=20
1. tìm xa, 2x - dfrac{1}{2} : dfrac{3}{4} dfrac{12}{9}b, x^2 - 2 02. Cho A dfrac{1,11+0,19-13.2}{2,06+0,54} - left(dfrac{1}{2}+dfrac{1}{4}right) : 2B left(5dfrac{7}{8}-2dfrac{1}{4}-0,5right) : 2dfrac{23}{26}a, Rút gọn A, Bb, Tìm x ϵ Z để A x B
Đọc tiếp
1. tìm x
a, 2x - \(\dfrac{1}{2}\) : \(\dfrac{3}{4}\) = \(\dfrac{12}{9}\)
b, x\(^2\) - 2 = 0
2. Cho
A = \(\dfrac{1,11+0,19-13.2}{2,06+0,54}\) - \(\left(\dfrac{1}{2}+\dfrac{1}{4}\right)\) : 2
B = \(\left(5\dfrac{7}{8}-2\dfrac{1}{4}-0,5\right)\) : \(2\dfrac{23}{26}\)
a, Rút gọn A, B
b, Tìm x ϵ Z để A < x < B
tim cap so x,y biet:
\(\dfrac{1+3.y}{12}\)\(=\dfrac{1+5.y}{5.x}\)\(=\dfrac{1+7.y}{4.x}\)
\(\left(3\dfrac{5}{7}x-1\dfrac{5}{7}x\right)-\dfrac{1}{3}=\dfrac{2}{3}\)
a)\(\dfrac{\left(x+\dfrac{3}{4}\right)\cdot\dfrac{7}{2}-\dfrac{1}{6}}{-\left(\dfrac{4}{5}+\dfrac{1}{3}\right)\cdot\dfrac{1}{2}+1}=2\dfrac{33}{52}\)
b)\(\dfrac{\left(5-\dfrac{2}{7}\right)\cdot\dfrac{7}{9}:\dfrac{3}{5}}{\left(3x-\dfrac{5}{6}\right):\dfrac{1}{7}}=5\dfrac{5}{21}\)
Bài 7: Tìm X
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)\(15\dfrac{1}{4}:\left(-\dfrac{5}{7}\right)-25\dfrac{1}{4}:\left(-\dfrac{5}{7}\right)\)
d)\(\left(-\dfrac{2}{3}+\dfrac{3}{7}\right):\dfrac{4}{5}+\left(\dfrac{-1}{3}+\dfrac{4}{7}\right):\dfrac{4}{5}\)