2.tìm x biết
a.\(\frac{4}{9}.x=\frac{9}{8}-0,125\)
b.\(\frac{x-12}{4}=\frac{1}{2}\)
c.3-\(\left(\frac{1}{6}-x\right).\frac{2}{3}=\frac{2}{3}\)
d.\(\frac{1}{2}.x+\frac{3}{5}.\left(x-2\right)=3\)
Tìm x, biết:
a)\(\frac{2}{9}:x + \frac{5}{6} = 0,5;\)
b)\(\frac{3}{4} - \left( {x - \frac{2}{3}} \right) = 1\frac{1}{3};\)
c)\(1\frac{1}{4}:\left( {x - \frac{2}{3}} \right) = 0,75;\)
d)\(\left( { - \frac{5}{6}x + \frac{5}{4}} \right):\frac{3}{2} = \frac{4}{3}\).
a)
\(\begin{array}{l}\frac{2}{9}:x + \frac{5}{6} = 0,5\\\frac{2}{9}:x = \frac{1}{2} - \frac{5}{6}\\\frac{2}{9}:x = \frac{3}{6} - \frac{5}{6}\\\frac{2}{9}:x = \frac{{ - 2}}{6}\\x = \frac{2}{9}:\frac{{ - 2}}{6}\\x = \frac{2}{9}.\frac{{ - 6}}{2}\\x = \frac{{ - 2}}{3}\end{array}\)
Vậy \(x = \frac{{ - 2}}{3}\).
b)
\(\begin{array}{l}\frac{3}{4} - \left( {x - \frac{2}{3}} \right) = 1\frac{1}{3}\\x - \frac{2}{3} = \frac{3}{4} - 1\frac{1}{3}\\x - \frac{2}{3} = \frac{3}{4} - \frac{4}{3}\\x - \frac{2}{3} = \frac{9}{{12}} - \frac{{16}}{{12}}\\x - \frac{2}{3} = \frac{{ - 7}}{{12}}\\x = \frac{{ - 7}}{{12}} + \frac{2}{3}\\x = \frac{{ - 7}}{{12}} + \frac{8}{{12}}\\x = \frac{1}{12}\end{array}\)
Vậy\(x = \frac{1}{12}\).
c)
\(\begin{array}{l}1\frac{1}{4}:\left( {x - \frac{2}{3}} \right) = 0,75\\\frac{5}{4}:\left( {x - \frac{2}{3}} \right) = \frac{3}{4}\\x - \frac{2}{3} = \frac{5}{4}:\frac{3}{4}\\x - \frac{2}{3} = \frac{5}{4}.\frac{4}{3}\\x - \frac{2}{3} = \frac{5}{3}\\x = \frac{5}{3} + \frac{2}{3}\\x = \frac{7}{3}\end{array}\)
Vậy \(x = \frac{7}{3}\).
d)
\(\begin{array}{l}\left( { - \frac{5}{6}x + \frac{5}{4}} \right):\frac{3}{2} = \frac{4}{3}\\ - \frac{5}{6}x + \frac{5}{4} = \frac{4}{3}.\frac{3}{2}\\ - \frac{5}{6}x + \frac{5}{4} = 2\\ - \frac{5}{6}x = 2 - \frac{5}{4}\\ - \frac{5}{6}x = \frac{8}{4} - \frac{5}{4}\\ - \frac{5}{6}x = \frac{3}{4}\\x = \frac{3}{4}:\left( { - \frac{5}{6}} \right)\\x = \frac{3}{4}.\frac{{ - 6}}{5}\\x = \frac{{ - 9}}{{10}}\end{array}\)
Vậy \(x = \frac{{ - 9}}{{10}}\).
Tìm x, biết:
a)\(x.\frac{{14}}{{27}} = \frac{{ - 7}}{9}\)
b)\(\left( {\frac{{ - 5}}{9}} \right):x = \frac{2}{3};\)
c)\(\frac{2}{5}:x = \frac{1}{{16}}:0,125\)
d)\( - \frac{5}{{12}}x = \frac{2}{3} - \frac{1}{2}\)
a)
\(\begin{array}{l}x.\frac{{14}}{{27}} = \frac{{ - 7}}{9}\\x = \frac{{ - 7}}{9}:\frac{{14}}{{27}}\\x = \frac{{ - 7}}{9}.\frac{{27}}{{14}}\\x = \frac{{ - 3}}{2}\end{array}\)
Vậy \(x = \frac{{ - 3}}{2}\).
b)
\(\begin{array}{l}\left( {\frac{{ - 5}}{9}} \right):x = \frac{2}{3}\\x = \left( {\frac{{ - 5}}{9}} \right):\frac{2}{3}\\x = \left( {\frac{{ - 5}}{9}} \right).\frac{3}{2}\\x = \frac{{ - 5}}{6}\end{array}\)
Vậy \(x = \frac{{ - 5}}{6}\).
c)
\(\begin{array}{l}\frac{2}{5}:x = \frac{1}{{16}}:0,125\\\frac{2}{5}:x = \frac{1}{{16}}:\frac{1}{8}\\\frac{2}{5}:x = \frac{1}{{16}}.8\\\frac{2}{5}:x = \frac{1}{2}\\x = \frac{2}{5}:\frac{1}{2}\\x = \frac{2}{5}.2\\x = \frac{4}{5}\end{array}\)
Vậy \(x = \frac{4}{5}\)
d)
\(\begin{array}{l} - \frac{5}{{12}}x = \frac{2}{3} - \frac{1}{2}\\ - \frac{5}{{12}}x = \frac{4}{6} - \frac{3}{6}\\ - \frac{5}{{12}}x = \frac{1}{6}\\x = \frac{1}{6}:\left( { - \frac{5}{{12}}} \right)\\x = \frac{1}{6}.\frac{{ - 12}}{5}\\x = \frac{{ - 2}}{5}\end{array}\)
Vậy \(x = \frac{{ - 2}}{5}\).
Chú ý: Khi trình bày lời giải bài tìm x, sau khi tính xong, ta phải kết luận.
1. tinh` giá trị biểu thức ( tính nhanh nếu có thế )
\(a)\frac{-6}{11}.\frac{5}{13}+\frac{-6}{11}.\frac{8}{13}-\left(\frac{-2}{5}\right)^0\) \(b)\left(2\frac{2}{3}+3\frac{1}{2}\right);\left(4\frac{3}{4}-2\frac{1}{6}\right)+\frac{19}{31}\) \(c)2,4:\left(-2\right)^3+\left(3-\frac{9}{11}\right).1\frac{3}{8}\)
\(d)\left(-\frac{3}{4}\right)^2:\frac{-3}{8}+\frac{1}{2}-\frac{3}{4}-\left(\frac{-78}{57}\right)^0\)
2. tìm x
\(a)x+\frac{-1}{5}=\left(-\frac{3}{4^{ }}\right)^2\) \(b)\left|\frac{5}{2}x+\frac{2}{3}\right|-\frac{1}{4}=0\) \(c)\frac{2}{3}x-\frac{1}{2}=\frac{5}{12}+\frac{1}{2}x\) \(d)\left(x-\frac{1}{4}\right)^4=\frac{1}{81}\)
\(e)4x+3\frac{1}{4}=x-\frac{1}{4}\) \(g)\left(x-\frac{1}{3}\right)^3=\frac{1}{27}\)
Tìm x :
a) \(\frac{3}{2}x-\frac{2}{3}=\frac{2}{3}:\frac{3}{2}\)
b) \(\left(\frac{9}{11}-x\right):\left(\frac{-10}{11}\right)=1-\frac{4}{5}\)
c) \(\frac{-11}{12}.x+\frac{3}{4}=\frac{-1}{6}\)
d) \(\frac{-5}{4}-\left(1\frac{1}{2}+x\right)=4,5\)
đ) \(\left(\frac{3}{4}-x:\frac{2}{15}\right).\frac{1}{5}=-2,6\)
e) \(3-\left(\frac{1}{6}-x\right).\frac{2}{3}=\frac{2}{3}\)
f) \(\left(1-2x\right).\frac{4}{5}=\left(-2\right)^3\)
g) \(\frac{1}{6}-\left|\frac{1}{2}.x-\frac{1}{3}\right|=\frac{1}{8}\)
Tìm x :
a) \(\frac{3}{2}x-\frac{2}{3}=\frac{2}{3}:\frac{3}{2}\)
b) \(\left(\frac{9}{11}-x\right):\left(\frac{-10}{11}\right)=1-\frac{4}{5}\)
c) \(\frac{-11}{12}.x+\frac{3}{4}=\frac{-1}{6}\)
d) \(\frac{-5}{4}-\left(1\frac{1}{2}+x\right)=4,5\)
đ) \(\left(\frac{3}{4}-x:\frac{2}{15}\right).\frac{1}{5}=-2,6\)
e) \(3-\left(\frac{1}{6}-x\right).\frac{2}{3}=\frac{2}{3}\)
f) \(\left(1-2x\right).\frac{4}{5}=\left(-2\right)^3\)
g) \(\frac{1}{6}-\left|\frac{1}{2}.x-\frac{1}{3}\right|=\frac{1}{8}\)
\(\frac{3}{2}x-\frac{2}{3}=\frac{2}{3}:\frac{3}{2}\)
\(\frac{3}{2}x-\frac{2}{3}=\frac{4}{9}\)
\(\frac{3}{2}x=\frac{4}{9}+\frac{2}{3}\)
\(\frac{3}{2}x=\frac{10}{9}\)
\(x=\frac{10}{9}:\frac{3}{2}\)
\(x=\frac{20}{27}\)
Vậy x=\(\frac{20}{27}\)
\(\left(\frac{9}{11}-x\right):\frac{-10}{11}=1-\frac{4}{5}\)
\(\left(\frac{9}{11}-x\right):\frac{-10}{11}=\frac{1}{5}\)
\(\frac{9}{11}-x=\frac{1}{5}\cdot\frac{-10}{11}\)
\(\frac{9}{11}-x=\frac{-2}{11}\)
\(x=\frac{9}{11}-\frac{-2}{11}\)
\(x=1\)
Vậy x=1
\(\frac{-11}{12}\cdot x+\frac{3}{4}=\frac{-1}{6}\)
\(\frac{-11}{12}\cdot x=\frac{-1}{6}-\frac{3}{4}\)
\(\frac{-11}{12}\cdot x=\frac{21}{12}\)
\(x=\frac{-21}{11}\)
Vậy x=\(\frac{-21}{11}\)
\(\frac{-5}{4}-\left(1\frac{1}{2}+x\right)=4,5\)
\(\frac{3}{2}+x=\frac{-5}{4}-\frac{9}{2}\)
\(\frac{3}{2}+x=\frac{23}{4}\)
\(x=\frac{17}{4}\)
Vậy x=\(\frac{17}{4}\)
\(\left(\frac{3}{4}-x:\frac{2}{15}\right)\cdot\frac{1}{5}=-2,6\)
\(\frac{3}{4}-x:\frac{2}{15}=\frac{-13}{5}:\frac{1}{5}\)
\(\frac{3}{4}-x:\frac{2}{15}=-13\)
\(x:\frac{2}{15}=\frac{3}{4}-\left(-13\right)\)
\(x:\frac{2}{15}=\frac{45}{4}\)
\(x=\frac{3}{2}\)
Vậy x=\(\frac{3}{2}\)
\(3-\left(\frac{1}{6}-x\right)\cdot\frac{2}{3}=\frac{2}{3}\)
\(3-\left(\frac{1}{6}-x\right)=\frac{2}{3}:\frac{2}{3}\)
\(3-\left(\frac{1}{6}-x\right)=1\)
\(\frac{1}{6}-x=2\)
\(x=\frac{1}{6}-2\)
\(x=\frac{-11}{6}\)
Vậy x=\(\frac{-11}{6}\)
\(\left(1-2x\right)\cdot\frac{4}{5}=\left(-2\right)^3\)
\(1-2x=\frac{-1}{10}\)
\(2x=1-\frac{-1}{10}\)
\(2x=\frac{11}{10}\)
\(x=\frac{11}{20}\)
Vậy x=\(\frac{11}{20}\)
\(\frac{1}{6}-\left|\frac{1}{2}\cdot x-\frac{1}{3}\right|=\frac{1}{8}\)
\(\left|\frac{1}{2}\cdot x-\frac{1}{3}\right|=\frac{7}{12}\)
\(\Rightarrow\frac{1}{2}x-\frac{1}{3}=\frac{7}{12}\) \(\frac{1}{2}x-\frac{1}{3}=\frac{-7}{12}\)
\(\frac{1}{2}x=\frac{11}{12}\) \(\frac{1}{2}x=\frac{-1}{4}\)
\(x=\frac{11}{6}\) \(x=\frac{-1}{2}\)
Vậy \(x\in\left\{\frac{11}{6};\frac{-1}{2}\right\}\)
\(\frac{3}{2}x-\frac{2}{3}=\frac{2}{3}:\frac{3}{2}\)
\(\frac{3}{2}x=\frac{4}{9}+\frac{6}{9}\)
\(\frac{3}{2}x=\frac{10}{9}\)
\(x=\frac{10}{9}:\frac{3}{2}\)
\(x=\frac{20}{27}\)
tk mình đi mình làm nốt cho hjhj ^^
Tìm x biết
a) (8-5x).(x+2)+4.(x-2).(x+1)+2.(x-2).(x+2)=0
b)\(\left(-\frac{2}{5}+x\right):\frac{7}{9}+\left(-\frac{3}{5}+\frac{5}{6}\right):\frac{7}{9}=0\)
c)\(1+\frac{1}{3}+\frac{1}{6}+\frac{1}{10}+...+\frac{2}{x\left(x+1\right)}=1\frac{2003}{2004}\)
ĐẠI SỐ
1. Giải các phương trình sau :
a) \(\frac{25x-655}{95}-\frac{5\left(x-12\right)}{209}=\frac{89-3x-\frac{2\left(x-18\right)}{5}}{11}\)
b) \(\frac{8\left(x+22\right)}{45}-\frac{7x+149+\frac{6\left(x+12\right)}{5}}{9}=\frac{x+35+\frac{2\left(x+50\right)}{9}}{5}\)
c) \(\frac{x+\frac{2\left(3-x\right)}{5}}{14}-\frac{5x-4\left(x-1\right)}{24}=\frac{7x+2+\frac{9-3x}{5}}{12}+\frac{2}{3}\)
2. Giải các bất phương trình sau :
a) \(5+\frac{x+4}{5}< x-\frac{x-2}{2}+\frac{x+3}{3}\)
b) \(x+1-\frac{x-1}{3}< \frac{2x+3}{2}+\frac{x}{3}+5\)
c) \(\frac{\left(3x-2\right)^2}{3}-\frac{\left(2x+1\right)^2}{3}\le x\left(x+1\right)\)
d) \(\frac{2x+3}{4}-\frac{x+1}{3}\ge\frac{1}{2}-\frac{3-x}{5}\)
\(\frac{25x-655}{95}-\frac{5\left(x-12\right)}{209}=\frac{89-3x-\frac{2\left(x-18\right)}{5}}{11}\)
\(< =>\frac{5x-131}{19}=\frac{1631-52x-\frac{38x-684}{5}}{209}\)
\(< =>\left(5x-131\right)209=\left(1631-52x-\frac{38x-684}{5}\right)19\)
\(< =>55x-1441=1631-52x-\frac{38x-684}{5}\)
\(< =>3072-107x=\frac{38x-684}{5}\)
\(< =>\left(3072-107x\right)5=38x-684\)
\(< =>15360-535x-38x-684=0\)
\(< =>14676=573x< =>x=\frac{14676}{573}=\frac{4892}{191}\)
nghệm xấu thế
\(\frac{8\left(x+22\right)}{45}-\frac{7x+149+\frac{6\left(x+12\right)}{5}}{9}=\frac{x+35+\frac{2\left(x+50\right)}{9}}{5}\)
\(< =>\frac{8x+176}{45}-\frac{41x+817}{45}=\frac{11x+415}{45}\)
\(< =>993-33x-11x-415=0\)
\(< =>578=44x< =>x=\frac{289}{22}\)
Bài 1:
b) Phương trình đã cho tương đương với phương trình:
\(\frac{8\left(x+22\right)-55\left(7x+149\right)-6\left(x+12\right)}{45}=\frac{9\left(x+35\right)+2\left(x+50\right)}{45}\)
\(\Leftrightarrow44x=-1056\)
\(\Leftrightarrow x=-24\)
Vậy x=-24 là nghiệm của phương trình
c) Phương trình đã cho tương đương với phương trình:
\(\frac{3x+6}{70}-\frac{x+4}{24}=\frac{32x+19}{60}+\frac{2}{3}\)
\(\Leftrightarrow12\left(3x+6\right)-35\left(x+4\right)=14\left(32x+19\right)+560\)
\(\Leftrightarrow-447x=894\)
\(\Leftrightarrow x=-2\)
Vậy x=-2 là nghiệm của phương trình
tìm x biết:
a,\(\left(\frac{1}{3}.x\right):\frac{2}{3}=1\frac{2}{3}:\frac{2}{5}\)
b,\(4,5:0,3=2,25:\left(0,1.x\right)\)
c,\(8:\left(\frac{1}{4}.x\right)=2:0,02\)
d,\(3:2\frac{1}{4}=\frac{3}{4}:\left(6.x\right)\)
e,\(3,8:\left(2.x\right)=\frac{1}{4}:2\frac{2}{3}\)
f,\(\left(0,25.x\right):3=\frac{5}{6}:0,125\)
g,\(1\frac{1}{3}:0,8=\frac{2}{3}:\left(0.1.x\right)\)
làm 1 bài mẫu nha
a) \(\left(\frac{1}{3}.x\right):\frac{2}{3}=\frac{25}{6}\)
\(\Rightarrow\frac{1}{3}x=\frac{25}{9}\)
\(\Rightarrow x=\frac{25}{9}:\frac{1}{3}\)
\(\Rightarrow x=\frac{25}{3}\)
các bài sau dễ lắm
a) \(\left(\frac{1}{3}x\right):\frac{2}{3}=1\frac{2}{3}:\frac{2}{5}\)
\(\Rightarrow\frac{1}{3}x:\frac{2}{3}=\frac{25}{6}\)
\(\Rightarrow\frac{1}{3}x=\frac{5}{3}\)
\(\Rightarrow x=\frac{5}{3}:\frac{1}{3}\)
\(\Rightarrow x=5\)
a) \(\left(\frac{1}{3}\cdot x\right):\frac{2}{3}=1\frac{2}{3}:\frac{2}{5}\)
\(\left(\frac{1}{3}\cdot x\right):\frac{2}{3}=\frac{25}{6}\)
\(\frac{1}{3}x=\frac{25}{6}\cdot\frac{2}{3}\)
\(\frac{1}{3}x=\frac{25}{9}\)
\(x=\frac{25}{9}:\frac{1}{3}\)
\(x=\frac{25}{3}\)
b) \(4,5:0,3=2,25:\left(0,1x\right)\)
\(15=2,25:\left(0,1x\right)\)
\(2,25:15=0,1x\)
\(0,15=0,1x\)
\(0,15:0,1=x\)
\(1,5=x\)
c) \(8:\left(\frac{1}{4}\cdot x\right)=2:0,02\)
\(8:\left(\frac{1}{4}\cdot x\right)=100\)
\(\frac{1}{4}\cdot x=8:100\)
\(\frac{1}{4}\cdot x=0,08\)
\(x=0,08:\frac{1}{4}\)
\(x=0,32\)
d) \(3:2\frac{1}{4}=\frac{3}{4}:\left(6\cdot x\right)\)
\(\frac{4}{3}=\frac{3}{4}:\left(6\cdot x\right)\)
\(\frac{3}{4}:\frac{4}{3}=6\cdot x\)
\(\frac{9}{16}=6\cdot x\)
\(\frac{9}{16}:6=x\)
\(\frac{3}{32}=x\)
e) \(3,8:\left(2\cdot x\right)=\frac{1}{4}:2\frac{2}{3}\)
\(3,8:\left(2\cdot x\right)=\frac{3}{32}\)
\(2\cdot x=3,8:\frac{3}{32}\)
\(2\cdot x=\frac{608}{15}\)
\(x=\frac{608}{15}:2\)
\(x=\frac{304}{15}\)
f) \(\left(0,25\cdot x\right):3=\frac{5}{6}:0,125\)
\(\left(0,25\cdot x\right):3=\frac{20}{3}\)
\(0,25\cdot x=\frac{20}{3}\cdot3\)
\(0,25\cdot x=20\)
\(x=20:0,25\)
\(x=80\)
g) \(1\frac{1}{3}:0,8=\frac{2}{3}:\left(0,1\cdot x\right)\)
\(\frac{5}{3}=\frac{2}{3}:\left(0,1\cdot x\right)\)
\(\frac{2}{3}:\frac{5}{3}=0,1\cdot x\)
\(\frac{2}{5}=0,1x\)
\(\frac{2}{5}:0,1=x\)
\(4=x\)
(Nhớ thử lại kết quả nhé)
bài 2 tìm x
a,\(\frac{-2}{3}.x+\frac{1}{5}=\frac{3}{10}\)
b,\(\left|x\right|-\frac{3}{4}=\frac{5}{3}\)
c,\(\frac{2}{3}.x-\frac{1}{2}=\frac{1}{10}\)
d,\(\frac{3}{5}+\frac{4}{9}:x=\frac{2}{3}\)
e,\(\left|x+75\%\right|=2\frac{1}{5}\)
i,\(\left(x+\frac{1}{2}\right).\left(\frac{2}{3}-2.x\right)=0\)
k,\(\frac{4}{7}.x-\frac{2}{3}=\frac{1}{5}\)
l,\(\frac{2}{3}.x-\frac{3}{2}.x=\frac{5}{12}\)
m,\(\left|2.x-\frac{1}{3}\right|+\frac{5}{6}=1\)
n,\(\frac{1}{3}-\frac{7}{8}.x=\frac{1}{3}\)
11,\(\frac{x+2}{5}=\frac{7}{12}-1\frac{1}{4}\)
12,\(\left(2\frac{4}{5}.x-50\right):\frac{2}{3}=51\)
13,\(\frac{2}{5}+\frac{3}{5}.\left(3.x-3,7\right)=-\frac{53}{10}\)
14,\(\frac{7}{9}:\left(2+\frac{3}{4}.x\right)+\frac{5}{9}=\frac{23}{27}\)