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0,7.2\(\frac23\).20.0,375.\(\frac{5}{28}\)
= \(\frac{7}{10}\) .\(\frac83\).20.\(\frac38\).\(\frac{5}{28}\)
= (\(\frac{7}{10}\).\(\frac{5}{28}\).20).(\(\frac83\).\(\frac38\))
= (\(\frac18.20\)). 1
= \(\frac52\)
B = (9,75 .21\(\frac37\) + \(\frac{39}{4}\).18\(\frac47\))
B = (\(\frac{39}{4}\).\(\frac{150}{7}\frac{}{7}\)+ \(\frac{39}{4}\).\(\frac{130}{7}\))
B = \(\frac{39}{4}\).(\(\frac{150}{7}\) + \(\frac{130}{7}\))
B = \(\frac{39}{4}\).\(\frac{280}{7}\)
B = 390
Tìm \(x\) câu a:
\(\frac13.x\) + \(\frac25.\left(x+1\right)\) = 0
\(\frac{5}{15}x\) + \(\frac{6}{15}x\) + \(\frac25\) = 0
\(\frac{11}{15}x\) = - \(\frac25\)
\(x=-\frac25:\frac{11}{15}\)
\(x\) = - \(\frac25\times\frac{15}{11}\)
\(x\) = - \(\frac{6}{11}\)
Vậy \(x=-\frac{6}{11}\)
Tìm \(x\) câu b:
\(x\) x 25% = 0,5
\(x\times0,25\) = 0,5
\(x=0,5:0,25\)
\(x=2\)
Vậy \(x=2\)
Câu 1a:
1/3x + 2/5(x + 1) = 0
1/3x + 2/5x + 2/5 = 0
1/3x + 2/5x = - 2/5
x(1/3 + 2/5) = -2/5
x.(5/15 + 6/15) = -2/5
x.11/15 = - 2/5
x = - 2/5 : 11/15
x = - 6/11
Vậy x = -6/11
Câu b:
x . 25%. x = 0,5
x.x = 0,5 : 25%
x^2 = 2
x = - \(\sqrt2\); x = \(\sqrt2\)
Vậy x ∈ {- \(\sqrt2\); \(\sqrt2\) )
Câu 1a:
1/3x + 2/5(x + 1) = 0
1/3x + 2/5x + 2/5 = 0
1/3x + 2/5x = - 2/5
x(1/3 + 2/5) = -2/5
x.(5/15 + 6/15) = -2/5
x.11/15 = - 2/5
x = - 2/5 : 11/15
x = - 6/11
Vậy x = -6/11
Câu b:
x . 25%. x = 0,5
x.x = 0,5 : 25%
x^2 = 2
x = - \(\sqrt2\); x = \(\sqrt2\)
Vậy x ∈ {- \(\sqrt2\); \(\sqrt2\) )
\(\frac{6}{11}x=\frac{9}{2}y=\frac{18}{5}z\Rightarrow\frac{6x}{11.18}=\frac{9y}{2.18}=\frac{18z}{5.18}\)
\(\Rightarrow\frac{-x}{-33}=\frac{y}{4}=\frac{z}{5}=\frac{-x+y+z}{-33+4+5}=\frac{-120}{-24}=5\)
\(\Rightarrow x=165;y=20;z=25\)
mik ko chép lại đề, mik làm luôn:
a) x - \(\frac{31}{36}=\frac{-13}{38}\)
x = \(\frac{-13}{18}+\frac{31}{36}\)
\(x=\frac{5}{36}\)
b)\(2-x-\frac{3}{7}=\frac{9}{-21}\)
\(\frac{11}{7}-x=\frac{3}{7}\)
x = \(\frac{11}{7}-\frac{3}{7}\)
x = 8/7
c) x + 3/11 = 23/44
x = 23/44 - 3/11
x = 1/4
d) \(\frac{1}{12}-x=\frac{-11}{9}\)
x = \(\frac{1}{12}+\frac{11}{9}\)
x = 47/36
e) \(x-\frac{2}{3}=\frac{-17}{3}\)
x= -17/3 + 2/3
x = -5
f) \(x-\frac{1}{2}=\frac{11}{4}.\frac{3}{11}\)
x - 1/2 = 3/4
x = 3/4 + 1/2
x = 5/4
g) \(2x+\frac{3}{8}=\frac{-21}{32}.\frac{4}{7}\)
2x + 3/8 = -3 / 8
2x = -3/8 - 3/8
2x = -9/8
x = -9/8.1/2
x = -9/16
h) x - \(\frac{x}{3}=\frac{3}{57}.\frac{19}{12}\)
x - \(\frac{x}{3}=\frac{1}{12}\)
x = \(\frac{1}{12}+\frac{x}{3}\)
x = \(\frac{1+4x}{12}\)
=> 12x = 1+4x
12x - 4x = 1
8x = 1
x = 1/8
Bài 2:
- \(\frac75\) + \(x\) = - \(\frac34\)
\(x\) = - \(\frac34+\frac75\)
\(x=-\frac{15}{20}\) + \(\frac{28}{20}\)
\(x\) = \(\frac{13}{20}\)
Vậy \(x=\frac{13}{20}\)
Bài 3:
- \(\frac74\) + \(\frac14:x\) = \(\frac32\)
\(\frac14:x\) = \(\frac32+\frac74\)
\(\frac14:x\) = \(\frac64+\frac74\)
\(\frac14:x=\frac{13}{4}\)
\(x=\frac14:\frac{13}{4}\)
\(x=\frac14\times\frac{4}{13}\)
\(x=\frac{1}{13}\)
Vậy \(x=\frac{1}{13}\)
\(\frac{5}{6}=\frac{15}{24}\)
\(\frac{4}{7}=\frac{12}{21}\)
\(\frac{3}{9}=\frac{7}{21}\)
\(\frac{-5}{-4}=\frac{20}{16}\)
5/6 = x/24 = 5*24 = 6*x = 120 = 6*x suy ra x= 120:6=20
4/7 = 12/x = 4*x = 7*12 = 4*x = 84 suy ra x= 84:4=21
3/x = 7/21 = 3/x = 1/3 = 3*3 = 1*x = 9 = 1*x suy ra x=9:1=9
x/-4 = 20/16 = x/-4 = 5/4 = x*4 = -4*5 = x*4 = -20 suy ra x=-20:4=-5
a) \(\frac{5}{6}\)= \(\frac{x}{24}\)
\(\Rightarrow\)\(x.6=24.5\)
x = \(\frac{24\cdot5}{6}\)
x=20
Vậy x = 20
b)\(\frac{4}{7}\)=\(\frac{20}{x}\)
\(\Rightarrow\)\(4\cdot x=20\cdot7\)
x= \(\frac{20\cdot7}{4}\)
x=35
Vậy x = 35
c)\(\frac{3}{x}\)=\(\frac{7}{21}\)
\(\Rightarrow\)\(x\cdot7=3\cdot21\)
x= \(\frac{3\cdot21}{7}\)
x= 9
Vậy x =9
d) \(\frac{x}{-4}\)=\(\frac{20}{16}\)
\(\Rightarrow\)\(x\cdot16=-4\cdot20\)
x= \(\frac{\left(-4\right)\cdot20}{16}\)
x =16
Vậy x = 16
CHÚC BẠN HỌC GIỎI
Nhật Minh là bạn làm khac mình thế ở câu b và câu d