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a ) \(x+x\times\frac{1}{3}\div\frac{2}{9}+x\div\frac{2}{7}=252\)
\(x\times1+x\times\frac{1}{3}\div\frac{2}{9}+x\div\frac{2}{7}=252\)
\(x\times1+x\times\frac{1}{3}\times\frac{9}{2}+x\times\frac{7}{2}=252\)
\(x\times1+x\times\frac{9}{6}+x\times\frac{7}{2}=252\)
\(x\times\left(1+\frac{9}{6}+\frac{7}{2}\right)=252\)
\(x\times6=252\)
\(x=252\div6\)
\(x=42\)
b ) \(\left(3\times x-0,8\right)\div x+14,5=15\)
\(\left(3\times x-0,8\right)\div x=15-14,5\)
\(\left(3\times x-0,8\right)\div x=0,5\)
\(0,8\div x=3-0,5\)
\(0,8\div x=2,5\)
\(x=0,8\div2,5\)
\(x=0,32\)
( 3 x - 0.8 ) : x + 14.5 = 15
( 3 x - 0.8 ) x \(\frac{1}{x}\)+ 14,5 = 15
3X x \(\frac{1}{x}\)- 0,8 x \(\frac{1}{x}\)= 0,5
\(\frac{3x}{x}-\frac{0,8}{x}=\frac{0,5x}{x}\)
=> 3x - 0,8 = 0,5x
3x - 0,5x = 0,8
2,5x = 0,8
x = 2,5 : 0,8
x = \(\frac{25}{8}=3,125\)
\((2,5\cdot x+2017)\cdot2018=(7,5+2017)\cdot2018\)
\(\Rightarrow(2,5\cdot x+2017)\cdot2018=4085441\)
\(\Rightarrow2,5\cdot x+2017=2024,5\)
\(\Rightarrow2,5x=7,5\)
\(\Rightarrow x=7,5:2,5=3\)
\(3\frac{1}{5}+\frac{2}{5}\left[x+\frac{1}{3}\right]=\frac{21}{5}\)
\(\Rightarrow\frac{16}{5}+\frac{2}{5}\left[x+\frac{1}{3}\right]=\frac{21}{5}\)
\(\Rightarrow\frac{2}{5}\left[x+\frac{1}{3}\right]=\frac{21}{5}-\frac{16}{5}\)
\(\Rightarrow\frac{2}{5}\left[x+\frac{1}{3}\right]=1\)
\(\Rightarrow x+\frac{1}{3}=\frac{5}{2}\)
\(\Rightarrow x=\frac{13}{6}\)
= 7 x 5 + 7 x 3,2 + 7 x 2,8 = 7 x (5 + 3,2 + 2,8) = 7 x (5 + 6) = 77
0.7 x 50 + 3.2 x 7 + 70 x 0.28
= (0.7 x 10) x (10 : 50) + (3.2 : 10) x ( 7.10 )+ 70 x 0.28
= 70 x 0.5 + 0. 32 x 70 + 70x0.28
=70 x ( 0.5 + 0.32 + 0.28 )
= 70 x 1.1
= 77
a)\(\frac{27}{5}\text{x}\frac{91}{12}\text{x}\frac{125}{9}\text{x}\frac{96}{13}=\frac{27}{9}\text{x}\frac{91}{13}\text{x}\frac{125}{5}\text{x}\frac{96}{12}=3\text{x}7\text{x}25\text{x}8\)
Đến đây tự tính nha !
b)\(\frac{2539}{35}\text{x}\frac{7}{90}+\frac{561}{35}\text{x}\frac{7}{90}=\frac{7}{90}\text{x}\left(\frac{2539}{35}+\frac{561}{35}\right)=\frac{7}{90}\text{x}\frac{3100}{35}=\frac{3100}{90}\text{x}\frac{7}{35}=\frac{310}{9}\text{x}\frac{1}{5}=\frac{62}{9}\)
a)0,48
b)0,4
a. 0.48
b. 0.4
chọn mình nha