tính bằng cách thuận tiện nhất : ( 36 + 54 ) x 8 + 8 x 9 + 8
nêu đầy đũ giúp em nhé
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(36 + 54) x 7 + 7 x 9 + 7
= 90 x 7 + 7 x 9 + 7
= (90 + 9 + 1 ) x 7
= 100 x 7
= 700
(36 + 54) x 7 + 7 x 9 + 7
= 90 x 7 + 7 x 9 + 7
= (90 + 9 + 1 ) x 7
= 100 x 7
= 700
a: \(=\dfrac{4}{3}\cdot\dfrac{32}{10}+\dfrac{8}{3}\cdot\dfrac{36}{10}-\dfrac{4}{10}\cdot\dfrac{12}{9}\)
\(=\dfrac{128}{30}+\dfrac{288}{30}-\dfrac{48}{90}=\dfrac{416}{30}-\dfrac{24}{30}=\dfrac{392}{30}=\dfrac{196}{15}\)
\(\dfrac{14}{9}\) x \(\dfrac{11}{8}-\dfrac{3}{8}\) x \(\dfrac{14}{9}\)
\(=\dfrac{14}{9}\) x \(\left(\dfrac{11}{8}-\dfrac{3}{8}\right)\)
\(=\dfrac{14}{9}\) x \(\dfrac{8}{8}=\dfrac{14}{9}\) x \(1\)
\(=\dfrac{14}{9}\)
\(419:\left(8\times8\times4,18+0,17\times2,5+2,09\times2\times36+0,23\times2,5\right)\)
\(=419:\left(64\times4,18+0,17\times2,5+4,18\times36+0,23\times2,5\right)\)
\(=419:\left[\left(64+36\right)\times4,18+\left(0,17+0,23\right)\times2,5\right]\)
\(=419:\left[100\times4,18+0,4\times2,5\right]\)
\(=419:\left[418+1\right]\)
\(=419:419\)
\(=1\)
\(=\dfrac{419}{64\cdot4.18+0,17\cdot2,5+2,09\cdot72+0,23\cdot2,5}\)
\(=\dfrac{419}{0,4\cdot2,5+64\cdot4,18+2,09\cdot72}\)
\(=\dfrac{419}{1+418}=1\)
6,25 X 8 + 6,25 : 0,5
= 6,25 x 8 + 6,25 x 2
= 6,25 x ( 8 + 2)
= 6,25 x 10
= 62,5
\(\dfrac{4}{5}\times\left(\dfrac{5}{4}-\dfrac{5}{7}\right)\)
\(=\dfrac{4}{5}\times\left(\dfrac{35}{28}-\dfrac{20}{28}\right)\)
\(=\dfrac{4}{5}\times\dfrac{15}{28}\)
\(=\dfrac{3}{7}\)
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\(\dfrac{5}{8}\times\dfrac{9}{7}+\dfrac{5}{8}\times\dfrac{5}{7}\)
\(=\dfrac{5}{8}\times\left(\dfrac{9}{7}+\dfrac{5}{7}\right)\)
\(=\dfrac{5}{8}\times2=\dfrac{10}{8}=\dfrac{5}{4}\)
\(\left(36+54\right)\times8+8\times9+8=90\times8+8\times9+8=\left(90+9+1\right)\times8=100\times8=800\)