Tính bằng cách thuận tiện nhất :
14 phần 15+3 phần 11+1 phần 15+3 phần 11+10 phần 12
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a) \(\frac{18}{15}+\frac{7}{15}+\frac{12}{15}\)
\(=\left(\frac{18}{15}+\frac{12}{5}\right)+\frac{7}{15}\)
\(=6+\frac{7}{15}\)
\(=\frac{97}{15}\)
b) \(\frac{9}{7}+\frac{8}{7}+\frac{11}{7}\)
\(=\frac{17}{7}+\frac{11}{7}\)
\(=\frac{28}{7}=4\)
TL
a) \(\frac{18}{15}+\frac{7}{15}+\frac{12}{15}\)\(=\frac{97}{15}\)
b) \(\frac{9}{7}+\frac{8}{7}+\frac{11}{7}\)\(=4\)
nha bn
HT
\(\frac{19}{11}+\left(\frac{8}{13}+\frac{3}{11}\right)=\frac{19}{11}+\frac{8}{13}+\frac{3}{11}\)
\(=\left(\frac{19}{11}+\frac{3}{11}\right)+\frac{8}{13}=2+\frac{8}{13}\)
\(=\frac{26}{13}+\frac{8}{13}=\frac{34}{13}\)
\(a.32,5-3\cdot0,87=32,5-2,61=29,89\)
\(8,5\cdot\left(1\dfrac{1}{2}+\dfrac{4}{4}\right):5=8,5\cdot\left(\dfrac{3}{2}+\dfrac{4}{4}\right):5\\ =8,5\cdot\left(\dfrac{6}{4}+\dfrac{4}{4}\right):5\\ =8,5\cdot\dfrac{10}{4}:5\\ =\dfrac{85}{4}:5\\ =\dfrac{17}{4}\)
\(b.30,96-6,45+14,4:3=30,96-6,45+4,8\\ =29,31\)
\(\dfrac{2}{5}\cdot\left(\dfrac{4}{5}-\dfrac{1}{2}\right)=\dfrac{2}{5}\cdot\left(\dfrac{8}{10}-\dfrac{5}{10}\right)\\ =\dfrac{2}{5}\cdot\dfrac{3}{10}=\dfrac{3}{25}\)
bài 2
\(a.2,5\cdot12,5\cdot8\cdot0,4=\left(2,5\cdot0,4\right)\left(12,5\cdot8\right)\\ =1\cdot100=100\)
b,\(\dfrac{12}{15}\cdot\dfrac{5}{6}\cdot\dfrac{3}{20}\cdot\dfrac{32}{5}=\dfrac{12\cdot5\cdot3\cdot32}{15\cdot6\cdot20\cdot5}\\ =\dfrac{3\cdot4\cdot5\cdot3\cdot4\cdot8}{3\cdot5\cdot2\cdot3\cdot5\cdot4\cdot5}=\dfrac{16}{25}\)
Bài 1:
a) \(32.5-3\cdot0.87=32.5-2.61=29.89\)
\(8.5\cdot\left(1\dfrac{1}{2}+\dfrac{4}{4}\right):5=8.5\cdot\dfrac{5}{2}:5=\dfrac{17}{2}\cdot\dfrac{5}{2}:5=\dfrac{85}{4}\cdot\dfrac{1}{5}=\dfrac{17}{4}\)
12/15 + 37/7 + 16/5 + 5/7
= 4/5 + 37/7 + 16/5 + 5/7
= (4/5 + 16/5) + (37/7 + 5/7)
= 4 + 6
= 10
Chúc bạn học tốt.
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b; \(\dfrac{5}{14}\) \(\times\) \(\dfrac{7}{13}\) x \(\dfrac{26}{25}\)
= \(\dfrac{5\times7\times2\times13}{7\times2\times13\times5\times5}\)
= \(\dfrac{5\times7\times2\times13}{5\times7\times2\times13}\) x \(\dfrac{1}{5}\)
= 1 x \(\dfrac{1}{5}\)
= \(\dfrac{1}{5}\)
14/15+3/11+1/15+3/11=10/22
=[14/15+1/15]+[3/11+3/11]
=[14/15+1/15]+[3/11*2]
= 1+6/11
=17/11
3/5 x 5 + 12 x 3/5 + 3 : 5/3
=3/5 x 5 + 12 x 3/5 + 3 x 3/5
= 3/5 x ( 5 + 12 + 3 )
= 3/5 x 20
= 12
14/15 + 3/11 + 1/15 + 3/11 + 10/12
= ( 3/11 + 3/11) + (14/15 + 1/15) + 5/6
= 6/11 + 1 + 5/6
= 6/11 + 5/6 +1
= 91/66 +1
=
Đ/S:
mình trình bày hơi xấu, xin lỗi nha
bạn tự tính 91/66 + 1 nha