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Gợi ý: Các biểu thức mũ chẵn đều không âm.
\(a^{2n}+b^{2n}\le0\Leftrightarrow a^{2n}+b^{2n}=0\Leftrightarrow a=b=0\)
a,\(\left(x-\frac{2}{5}\right)^{2010}+\left(y+\frac{3}{7}\right)^{468}\)< \(0\)
Vì \(\left(x-\frac{2}{5}\right)^{2010}\);\(\left(y+\frac{3}{7}\right)^{468}\)đều > \(0\)
=> \(\left(x-\frac{2}{5}\right)^{2010}=0\)
\(\left(y+\frac{3}{7}\right)^{468}=0\)
=> \(\left(x-\frac{2}{5}\right)^{2010}=0^{2010}\)
\(\left(y+\frac{3}{7}\right)^{468}=0^{468}\)
=> \(x-\frac{2}{5}=0\)
\(y-\frac{3}{7}=0\)
=> \(x=\frac{2}{5}\)
\(y=\frac{3}{7}\)
Vậy \(x=\frac{2}{5}\)\(y=\frac{3}{7}\)
a) \(\frac{37-2\times\left(y-3,25\right)}{5}=7,06\)
=> \(37-2\times\left(y-3,25\right)=7,06\times5\)
=> \(37-2\times\left(y-3,25\right)=35,3\)
=> \(2\times\left(y-3,25\right)=37-35,3=1,7\)
=> \(y-3,25=1,7:2=0,85\)
=> y = 0,85 + 3,25 = 4,1
Tới khúc này là dẫn đến tìm x chứ không tìm y nx ...
Sửa câu b lại đi
c) \(\frac{5}{12}\times\left(8+x\right)-\frac{1}{5}\times\left(\frac{15}{4}+x\right)=15\)
=> \(\frac{10}{3}+\frac{5}{12}x-\frac{3}{4}+\frac{1}{5}x=15\)
=> \(\left(\frac{10}{3}-\frac{3}{4}\right)-\left(\frac{5}{12}x-\frac{1}{5}x\right)=15\)
=> \(\frac{31}{12}+\frac{13}{60}x=15\)
=> \(\frac{13}{60}x=15-\frac{31}{12}=\frac{149}{12}\)
=> \(x=\frac{149}{12}:\frac{13}{60}=\frac{149}{12}\cdot\frac{60}{13}=\frac{745}{13}\)
Làm nốt câu d nhé
1, \(\frac{1}{2}-\left(6\frac{5}{9}+x-\frac{117}{8}\right):\left(12\frac{1}{9}\right)=0\)
\(\left(\frac{6.9+5}{9}+x-\frac{117}{8}\right):\frac{12.9+1}{9}=\frac{1}{2}\)
( . là nhân nha)
\(\left(\frac{59}{9}-\frac{117}{8}+x\right):\frac{109}{9}=\frac{1}{2}\)
\(\frac{59}{9}-\frac{117}{8}+x=\frac{1}{2}\cdot\frac{109}{9}\)
\(\frac{59}{9}-\frac{117}{8}+x=\frac{109}{18}\)
\(x=\frac{109}{18}-\frac{59}{9}+\frac{117}{8}\)
\(x=\frac{113}{8}\)
( \(\left(y+\frac{1}{3}\right)+\left(y+\frac{2}{9}\right)+\left(y+\frac{1}{27}\right)+\left(y+\frac{1}{81}\right)=\frac{56}{81}\)
\(y+\frac{1}{3}+y+\frac{2}{9}+y+\frac{1}{27}+y+\frac{1}{81}=\frac{56}{81}\)
\(4y+\frac{1}{3}+\frac{2}{9}+\frac{1}{27}+\frac{1}{81}=\frac{56}{81}\)
\(4y+\frac{49}{81}=\frac{56}{81}\)
\(4y=\frac{7}{81}\)
y = 7/81:4
y = 7/324
b, (y+1) + (y+2) + (y+3) + .... + (y+99) = 6138
(y+y+y+y+....+y) + (1+2+3+...+99) = 6138
99.y + 4950 = 6138
99.y = 6138 - 4950
99.y = 1188
y = 1188 : 99
x = 12
a) \(\left(y+1\right)+\left(y+4\right)+\left(y+7\right)+....+\left(y+28\right)=155155\)
\(\Rightarrow\left(y+y+...+y\right)+\left(1+4+7+...+28\right)=155155\)
\(\Rightarrow10x+145=155155\)
\(\Rightarrow10x=155010\)
\(\Rightarrow x=15501\)
Vậy x = 15501
b) \(\left(y+1\right)+\left(y+2\right)+..+\left(y+99\right)=6138\)
\(\Rightarrow\left(y+y+...+y\right)+\left(1+2+3+...+99\right)=6138\)
\(\Rightarrow99x+4950=6138\)
\(\Rightarrow99x=1188\)
\(\Rightarrow x=12\)
Vậy x = 12