Tính :
9 - 3 : 1/3 + 1 = ?
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Tính:
2/7 + 5/7=1
8/15 + 6/15 =14/15
2/9 + 3/9 + 4/9=9/9=1
[ Không cần làm phép tính ]Điền vào ô trống <,>,= :
3/5 + 1/5 = 1/5 + 3/5
7/9 + 1/9 < 7/9 + 1/9 + 1/9
3/7 + 2/7 < 3/7 + 4/7
1/5 + 3/5 < 2/5 + 3/5
Tính:
2/7 + 5/7=1
8/15 + 6/15 =14/15
2/9 + 3/9 + 4/9=9/9=1
[ Không cần làm phép tính ]Điền vào ô trống <,>,= :
3/5 + 1/5 = 1/5 + 3/5
7/9 + 1/9 < 7/9 + 1/9 + 1/9
3/7 + 2/7 < 3/7 + 4/7
1/5 + 3/5 < 2/5 + 3/5
a) \(\left(\dfrac{3}{29}-\dfrac{1}{5}\right)\cdot\dfrac{29}{3}\)
\(=\dfrac{3}{29}\cdot\dfrac{29}{3}-\dfrac{1}{5}\cdot\dfrac{29}{3}\)
\(=1-\dfrac{29}{15}\)
\(=\dfrac{15-29}{15}\)
\(=-\dfrac{14}{15}\)
b) \(\dfrac{3}{4}\cdot\dfrac{7}{9}+\dfrac{1}{4}\cdot\dfrac{7}{9}\)
\(=\dfrac{7}{9}\cdot\left(\dfrac{1}{4}+\dfrac{3}{4}\right)\)
\(=\dfrac{7}{9}\cdot1\)
\(=\dfrac{7}{9}\)
c) \(\dfrac{1}{7}\cdot\dfrac{5}{9}+\dfrac{5}{9}\cdot\dfrac{1}{7}+\dfrac{5}{9}\cdot\dfrac{3}{7}\)
\(=\dfrac{5}{9}\cdot\left(\dfrac{1}{7}+\dfrac{1}{7}+\dfrac{3}{7}\right)\)
\(=\dfrac{5}{9}\cdot\dfrac{5}{7}\)
\(=\dfrac{25}{63}\)
d) \(4\cdot11\cdot\dfrac{3}{4}\cdot\dfrac{9}{121}\)
\(=\left(4\cdot\dfrac{3}{4}\right)\cdot\left(11\cdot\dfrac{9}{121}\right)\)
\(=3\cdot\dfrac{9}{11}\)
\(=\dfrac{27}{11}\)
\(A=\frac{1}{3}+\frac{1}{3+6}+\frac{1}{3+6+9}+...+\frac{1}{3+6+9+...+2013}\)
\(A=\frac{1}{3}.\left(1+\frac{1}{1+2}+\frac{1}{1+2+3}+...+\frac{1}{1+2+3+...671}\right)\)
\(A=\frac{1}{3}.\left(\frac{1}{\left(1+0\right).2:2}+\frac{1}{\left(1+2\right).2:2}+\frac{1}{\left(1+3\right).3:2}+...+\frac{1}{\left(1+671\right).671:2}\right)\)
\(A=\frac{1}{3}.\left(\frac{2}{1.2}+\frac{2}{2.3}+\frac{2}{3.4}+...+\frac{2}{671.672}\right)\)
\(A=\frac{1}{3}.2.\left(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{671.672}\right)\)
\(A=\frac{2}{3}.\left(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{671}-\frac{1}{672}\right)\)
\(A=\frac{2}{3}.\left(1-\frac{1}{672}\right)\)
\(A=\frac{2}{3}.\frac{671}{672}=\frac{671}{1008}\)
Tính
b)
1 + 9 = 2 + 8 = 3 + 7 = 4 + 6 =
9 + 1 = 8 + 2 = 7 + 3 = 6 + 4 =
9 - 1 = 8 - 2 = 7 - 3 = 6 - 3 =
b)
1 + 9 = 10 2 + 8 = 10 3 + 7 = 10 4 + 6 = 10
9 + 1 = 10 8 + 2 = 10 7 + 3 = 10 6 + 4 = 10
9 - 1 = 8 8 - 2 = 6 7 - 3 = 4 6 - 3 = 3
8 + 1 = 9 7 + 2 = 9 6 + 3 = 9 5 + 4 = 9
1 + 8 = 9 2 + 7 = 9 3 + 6 = 9 4 + 5= 9
9 - 8 = 1 9 - 7 = 2 9 - 6 = 3 9 - 5 = 4
9 - 1 = 8 9 - 2 = 7 9 - 3 = 6 9 - 4 = 5
1 / 9 + 2 / 9 + 4 / 9 = 7 / 9
5 / 5 + 6 / 5 + 1 = 15 / 5 = 3
12 / 2 + 4 / 2 + 1 + 3 / 2 = 21 / 2
7 / 3 + 6 / 3 + 1 + 1 = 19 / 3
3/4 x 2/9 + 1/5 = 1/6 + 1/5 = 5/30 + 6/30 = 11/30
7/9 - ( 1/3 : 3/5 ) = 7/9 - ( 1/3 x 5/3 ) = 7/9 - 5/9 = 2/9
trả lời
9-3:1/3+1
=9-(3:1/3)+1
=9-9+1
=1
hc tốt
\(9-3:\frac{1}{3}+1=9-3\times3+1=9-9+1=1\)
HOK TOT