34*7
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16 tháng 11 2021 lúc 14:04
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Bài 7. Tính nhanh giá trị biểu thức: 34 × 12 + 34 × 7 – 34 × 9:
C. 2400
D. 3210
B. 3400
A. 340
tìm giá trị của biểu thức sau A= (1/7 +1/23 -1/1009):( 1/23 +1/7-1/1009 + 1/7 .1/23.1/1009) +1:(30.1009-160)
15/34+7/21+19/34-1 7/21+2/5
\(\dfrac{15}{34}+\dfrac{7}{21}+\dfrac{19}{34}-1\dfrac{7}{21}+\dfrac{2}{5}=\left(\dfrac{15}{34}+\dfrac{19}{34}\right)+\left(\dfrac{7}{21}-\dfrac{4}{3}\right)+\dfrac{2}{5}=1+\left(-1\right)+\dfrac{2}{5}=0+\dfrac{2}{5}=\dfrac{2}{5}\)
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Tính giá trị biểu thức : a) A = (-13) + (-27) + (-65); b) B = (-9) + (-14) + 27; c) C = |-7 + 11| + |-11 + 7| = 11 + (-7)|; d) D - [(-21)+(-34)]+[(-21)+34]+[-34 + 21].
20/34 + 7/21 + 19/34 - 20/15 + 3/7=?
Tính hợp lý : a)2/7+5/7×7/10-1/14 b)(3 1/2-2/3)×7/34-5/34
\(a,\dfrac{2}{7}+\dfrac{5}{7}.\dfrac{7}{10}-\dfrac{1}{14}\)
\(=\dfrac{1}{7}.2+\dfrac{1}{7}.5.\dfrac{7}{10}-\dfrac{1}{7}.\dfrac{1}{2}\)
\(=\dfrac{1}{7}.\left(2+\dfrac{35}{10}-\dfrac{1}{2}\right)\)
\(=\dfrac{1}{7}.\left(\dfrac{4}{2}+\dfrac{7}{2}-\dfrac{1}{2}\right)\)
\(=\dfrac{1}{7}.5=\dfrac{5}{7}\)
\(b,\left(3\dfrac{1}{2}-\dfrac{2}{3}\right).\dfrac{7}{34}-\dfrac{5}{34}\)
\(=\left(\dfrac{7}{2}-\dfrac{2}{3}\right).\dfrac{7}{34}-\dfrac{7}{34}.\dfrac{5}{7}\)
\(=\dfrac{7}{34}.\left(\dfrac{17}{6}-\dfrac{5}{7}\right)\)
\(=\dfrac{7}{34}.\dfrac{89}{42}=\dfrac{89}{204}\)
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a: =2/7-1/14+5/10
=2/7-1/14+1/2
=4/14-1/14+7/14
=10/14=5/7
b: =(7/2-2/3)*7/34-5/34
\(=\dfrac{21-4}{6}\cdot\dfrac{7}{34}-\dfrac{5}{34}\)
\(=\dfrac{7}{6}\cdot\dfrac{1}{2}-\dfrac{5}{34}=\dfrac{7}{12}-\dfrac{5}{34}=\dfrac{89}{204}\)
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15/34 + 7/21 + 19/34 - 20/15 + 3/7
\(\frac{15}{34}+\frac{7}{21}+\frac{19}{34}-\frac{20}{15}+\frac{3}{7}\)
\(=\left(\frac{15}{34}+\frac{19}{34}\right)+\left(\frac{7}{21}-\frac{20}{15}\right)+\frac{3}{7}\)
\(=1+1+\frac{3}{7}=2\frac{3}{7}=\frac{17}{7}\)
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15 phần 34 + 7 phần 21 +19 phần 34 - 20 phần 15 +3 phần 7 = ?
\(\frac{15}{34}+\frac{7}{21}+\frac{19}{34}-\frac{20}{15}+\frac{3}{7}\)
\(\frac{15}{34}+\frac{1}{3}+\frac{19}{34}+\left(-\frac{4}{3}\right)+\frac{3}{7}\)
\(\left(\frac{15}{34}+\frac{19}{34}\right)+\left(\frac{1}{3}-\frac{4}{3}\right)+\frac{3}{7}\)
\(1+\left(-1\right)+\frac{3}{7}\)
\(=0+\frac{3}{7}=\frac{3}{7}\)
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\(\frac{15}{34}+\frac{7}{21}+\frac{19}{34}-\frac{20}{15}+\frac{3}{7}\)
\(=\)\(\frac{15}{34}+\frac{1}{3}+\frac{19}{34}+\left(-\frac{4}{3}\right)+\frac{3}{7}\)
\(=\)\(\left(\frac{15}{34}+\frac{19}{34}\right)+\left(\frac{1}{3}-\frac{4}{3}\right)+\frac{3}{7}\)
\(=\)\(1+\left(-1\right)+\frac{3}{7}\)
\(=\)\(0+\frac{3}{7}\)
\(=\)\(\frac{3}{7}\)
15/34+7/21+19/34-20/15
=15/34+19/34+1/3-4/3
=1-1
=0
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19 /34 + 7/21 + 15/34 - 20/15 +3/7 = ?