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\(\text{a)}\left(2^{17}+17^2\right)\left(9^{15}-15^9\right)\left(4^2-2^4\right)\)
\(=\left(2^{17}+17^2\right)\left(9^{15}-15^9\right)\left[\left(2^2\right)^2-2^4\right]\)
\(=\left(2^{17}+17^2\right)\left(9^{15}-15^9\right)\left(2^4-2^4\right)\)
\(=\left(2^{17}-17^2\right)\left(9^{15}-15^9\right).0\)
\(=0\)
\(\text{b)}\left(7^{1997}-7^{1995}\right):\left(7^{1994}.7\right)=\frac{7^{1997}-7^{1995}}{7^{1994}.7}=\frac{7^{1995}\left(7^2-1\right)}{7^{1995}}=7^2-1=48\)
\(\frac{\frac{2}{3}+\frac{2}{5}-\frac{2}{9}}{\frac{4}{3}+\frac{4}{5}-\frac{4}{9}}\) _ \(\frac{3-\frac{3}{11}-\frac{3}{17}}{5-\frac{5}{11}-\frac{5}{17}}\)
=\(\frac{2\left(\frac{1}{3}+\frac{1}{5}-\frac{1}{9}\right)}{4\left(\frac{1}{3}+\frac{1}{5}-\frac{1}{9}\right)}\)_ \(\frac{3\left(1-\frac{1}{11}-\frac{1}{17}\right)}{5\left(1-\frac{1}{11}-\frac{1}{17}\right)}\)= \(\frac{2}{4}-\frac{3}{5}\)= \(\frac{-1}{10}\)
a)\(\frac{2}{3}+\frac{3}{4}+\frac{5}{6}\)
\(=\frac{8+9+10}{12}\)
\(=\frac{27}{12}=\frac{9}{4}\)
b)\(\frac{15}{8}-\frac{7}{12}+\frac{5}{6}\)
\(=\frac{45-14+20}{24}\)
\(=\frac{51}{24}=\frac{17}{8}\)
2)
a)\(\frac{2}{5}+\frac{7}{13}+\frac{3}{5}+\frac{1}{7}\)
\(=\frac{2}{5}+\frac{3}{5}+\frac{7}{13}+\frac{1}{7}\)
\(=1+\frac{7}{13}+\frac{1}{7}\)
\(=\frac{20}{13}+\frac{1}{7}\)
\(=\frac{153}{91}\)
Tí tớ trả lời tiếp
a , 43 . 125 - 125 . 60
= 125 . ( 43 - 60)
= 125 . ( 64 - 60)
= 125 . 4
= 500
b , -23 + [82 - (-15-17)]
= -23 + (82 +28)
=-23 + 110
= 87
a, 2 17 + 17 2 9 15 - 3 15 2 4 - 4 2
= 2 17 + 17 2 9 15 - 3 15 16 - 16
= 2 17 + 17 2 9 15 - 3 15 . 0
= 0
b, 1 2 + 2 3 + 3 4 + 4 5 . ( 1 3 + 2 3 + 3 3 + 4 3 ) ( 3 8 - 81 2 )
= 1 2 + 2 3 + 3 4 + 4 5 . ( 1 3 + 2 3 + 3 3 + 4 3 ) ( 3 4 . 2 - 81 2 )
= 1 2 + 2 3 + 3 4 + 4 5 . ( 1 3 + 2 3 + 3 3 + 4 3 ) ( 81 2 - 81 2 )
= 1 2 + 2 3 + 3 4 + 4 5 . ( 1 3 + 2 3 + 3 3 + 4 3 ) . 0
= 0
c, 7 24 + 7 23 : 7 22
= 7 24 : 7 22 + 7 23 : 7 22
= 7 24 - 22 + 7 23 - 22
= 7 2 + 7 1
= 49 + 7 = 56