tính bằng cách thuận tiện 7.5*12+3*24.5*4-6*12*12
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\(7,5\times12+3\times24,5\times4-6\times12\times2\)
\(=7,5\times12+\left(3\times4\right)\times24,5-\left(6\times2\right)\times12\)
\(=7,5\times12+12\times24,5-12\times12\)
\(=12\times\left(7,5+24,5-12\right)\)
\(=12\times20\)
\(=240\)
\(7,5\times12+3\times24,5\times4-6\times12\times2\)
\(=7,5\times12+12\times24,5-12\times12\)
\(=12\times\left(7,5+24,5-12\right)\)
\(=12\times20\)
\(=240\)
a) 8 × 5 × 9 = (8 × 5) × 9 = 40 × 9 = 360
b) 6 × 7 × 5 = (6 × 5) × 7= 30 × 7= 210
c) 6 × 4 × 25 = 6 × (4 × 25) = 6 × 100= 600
3/4 x 7/12 + 3/4 x 1/6 + 3/4 x 1/4
=3/4 x (7/12 + 1/6 + 1/4)
=3/4 x (7/12 + 2/12 + 3/12)
=3/4 x 1
=3/4
Chúc học tốt~
\(\frac{14}{9}:\frac{13}{12}+\frac{4}{3}:\frac{13}{12}\)
\(=\frac{14}{9}\cdot\frac{12}{13}+\frac{4}{3}\cdot\frac{12}{13}\)
\(=\left(\frac{14}{9}+\frac{4}{3}\right)\cdot\frac{12}{13}\)
\(=\frac{26}{9}\cdot\frac{12}{13}=\frac{8}{3}\)
\(4\cdot5\cdot\frac{6}{12}\cdot10\cdot8=\left(4\cdot5\right)\cdot\left(\frac{6}{12}\cdot8\right)\cdot10\)
\(=20\cdot4\cdot10=800\)
\(\frac{4\times5\times6}{12\times10\times8}=\frac{4\times5\times6}{2\times6\times5\times2\times2\times4}=\frac{1}{2\times2\times2}=\frac{1}{8}\)
\(\frac{4x5x6}{12x10x8}\)=\(\frac{1x1x1}{2x2x2}\)= \(\frac{1}{8}\)
\((\frac{1}{2}+\frac{1}{4}+\frac{1}{6}) \)x \((\frac{36}{9}-\frac{12}{9}:\frac{1}{3}) \)
\(= (\frac{1}{2}+\frac{1}{4}+\frac{1}{6}) \) x \((\frac{36}{9}-\frac{36}{9})\)
\( = (\frac{1}{2}+\frac{1}{4}+\frac{1}{6}) \) x \(0\)
\(= 0\)
\(3\cdot15\cdot4+12\cdot19+6\cdot66\cdot2\)
\(=\left(3\cdot4\right)\cdot15+12\cdot19+\left(6\cdot2\right)\cdot66\)
\(=12\cdot15+12\cdot19+12\cdot66\)
\(=12\cdot\left(15+19+66\right)\)
\(=12\cdot100\)
\(=1200\)
\(3.15.4+1.19+6.66.2\)
= ( 3. 4 ) . 15 + 12 .19 - (6.2) . 66
= 12 . 15 + 12 . 19 + 12 . 66
= 12.(15 + 19 + 66)
= 2 . 100
= 1200
\(\frac{1}{2}+\frac{2}{4}+\frac{3}{6}+\frac{4}{8}+\frac{5}{10}+\frac{6}{12}\)
\(=\frac{1}{2}+\frac{1}{2}+\frac{1}{2}+\frac{1}{2}+\frac{1}{2}+\frac{1}{2}\)
\(=6\times\frac{1}{2}=3\)
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