tính bằng cách thuận tiện:
a, 3/4 + 2/5 + 3/12 b, 47/15 +40/17 - 4/30 - 6/17
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a)=(3/4+3/12)+2/5
=1+2/15
=17/15
b)
(40/17-6/17)+(47/15-4/30)
=2+3=5
k cho minh
Tinh1 bằng cách thuận tiện nhất :
a ) 3/4 + 2/5 + 3/12
= 3/4 + 2/5 + 1/4
= ( 3/4 + 1/4 ) + 2/5
= 1 + 2/5
= 2/5
b ) 47/15 + 40/17 - 4/30 - 6/17
= 47/15 + 40/17 - 2/15 - 6/17
= ( 47/15 - 2/15 ) + ( 40/17 - 6/17 )
= 45/15 + 34 /17
= 3 + 2
= 5
tk mk nha
thấy thế nào , comment đi
yêu mọi người nhiều lắm !!!
\(1,\\ c,\dfrac{17}{6}-\dfrac{3}{7}-\dfrac{5}{6}=\dfrac{17\times7-3\times6-5\times7}{6\times7}=\dfrac{119-18-35}{42}=\dfrac{66}{42}=\dfrac{11}{7}\\ 2,\\ a,\dfrac{6}{9}+\dfrac{3}{15}+\dfrac{7}{15}\\ =\dfrac{6:3}{9:3}+\dfrac{7+3}{15}\\ =\dfrac{2}{3}+\dfrac{10}{15}\\ =\dfrac{2}{3}+\dfrac{2}{3}\\ =\dfrac{2+2}{3}=\dfrac{4}{3}\)
\(b,\dfrac{7}{2}+\dfrac{29}{12}-\dfrac{11}{12}\\ =\dfrac{7}{2}+\left(\dfrac{29}{12}-\dfrac{11}{12}\right)\\ =\dfrac{7}{2}+\dfrac{29-11}{12}\\ =\dfrac{7}{2}+\dfrac{18}{12}\\ =\dfrac{7}{2}+\dfrac{18:6}{12:6}\\ =\dfrac{7}{2}+\dfrac{3}{2}\\ =\dfrac{7+3}{2}=\dfrac{10}{2}=5\)
\(c,\dfrac{26}{25}-\dfrac{3}{5}-\dfrac{2}{5}\\ =\dfrac{26}{25}-\dfrac{3\times5}{5\times5}-\dfrac{2\times5}{5\times5}\\ =\dfrac{26-15-10}{25}\\ =\dfrac{1}{25}\)
Bài 1:
\(\dfrac{17}{6}-\dfrac{3}{7}-\dfrac{5}{6}=\left(\dfrac{17}{6}-\dfrac{5}{6}\right)-\dfrac{3}{7}=2-\dfrac{3}{7}=\dfrac{14}{7}-\dfrac{3}{7}=\dfrac{11}{7}\)
Bài 2:
a/\(\dfrac{6}{9}+\dfrac{3}{15}+\dfrac{7}{15}\)
\(=\dfrac{2}{3}+\left(\dfrac{3}{15}+\dfrac{7}{15}\right)\)
\(=\dfrac{2}{3}+\dfrac{2}{3}\)
\(=\dfrac{4}{3}\)
b/\(\dfrac{7}{2}+\dfrac{29}{12}-\dfrac{11}{12}\)
\(=\dfrac{7}{2}+\left(\dfrac{29}{12}-\dfrac{11}{12}\right)\)
\(=\dfrac{7}{2}+\dfrac{3}{2}\)
\(=5\)
c/\(\dfrac{26}{25}-\dfrac{3}{5}-\dfrac{2}{5}\)
\(=\dfrac{26}{25}-\left(\dfrac{3}{5}+\dfrac{2}{5}\right)\)
\(=\dfrac{26}{25}-1\)
\(=\dfrac{26}{25}-\dfrac{25}{25}\)
\(=\dfrac{1}{25}\)
#Đang Bận Thở
đầu tiên được `1/15 tiếp theo kết quả được`1/4` và
được `5`
a) 15 / 17 x 4 / 7 + 15 / 17 x 3 / 7
= 15 / 17 x (4 / 7 + 3 / 7)
=15 / 17 x 1=15 / 17
b) 29 / 12 : 1 / 2 - 5 / 12 :1 / 2
=29 / 12 x2 - 5 / 12 x 2
=(29 / 12 - 5 / 12)x2
=2x2=4
a) 15 / 17 x 4 / 7 + 15 / 17 x 3 / 7
= 15 / 17 x (4 / 7 + 3 / 7)
=15 / 17 x 1=15 / 17
b) 29 / 12 : 1 / 2 - 5 / 12 :1 / 2
=29 / 12 x2 - 5 / 12 x 2
=(29 / 12 - 5 / 12)x2
=2x2=4
chúc bạn học tốt !
\(\frac{3}{5}\times\frac{6}{7}+\frac{3}{5}:7+\frac{6}{5}\)
\(=\frac{3}{5}\times\frac{6}{7}+\frac{3}{5}\times\frac{1}{7}+\frac{6}{5}\)
\(=\frac{3}{5}\times\left(\frac{6}{7}+\frac{1}{7}\right)+\frac{6}{5}\)
\(=\frac{3}{5}\times1+\frac{6}{5}\)
\(=\frac{3}{5}+\frac{6}{5}=\frac{9}{5}\)
~ Hok tốt ~
\(\frac{29}{12}:\frac{1}{2}-\frac{5}{12}:\frac{1}{2}-\frac{1}{2}\)
\(=\left(\frac{29}{12}-\frac{5}{12}\right):\frac{1}{2}-\frac{1}{2}\)
\(=2:\frac{1}{2}-\frac{1}{2}\)
\(=4-\frac{1}{2}=\frac{7}{2}\)
~ Hok tốt ~
a) \(\frac{5}{6}-\left(\frac{2}{5}+\frac{1}{3}\right)=\frac{5}{6}-\frac{11}{15}=\frac{1}{10}\)
b) \(\frac{3}{4}-\frac{1}{3}-\frac{1}{6}=\frac{3}{4}-\left(\frac{1}{3}+\frac{1}{6}\right)=\frac{3}{4}-\frac{1}{2}=\frac{1}{4}\)
a, \(\frac{5}{6}-\left(\frac{2}{5}+\frac{1}{3}\right)\)
\(=\frac{5}{6}-\frac{2}{5}-\frac{1}{3}\)
\(=\frac{25}{30}-\frac{12}{30}-\frac{10}{30}\)
\(=\frac{3}{30}=\frac{1}{10}\)
b. \(\frac{3}{4}-\frac{1}{3}-\frac{1}{6}\)
\(=\frac{3}{4}-\left(\frac{1}{3}+\frac{1}{6}\right)\)
\(=\frac{3}{4}-\frac{9}{18}\)
\(=\frac{3}{4}-\frac{1}{2}\)
\(=\frac{1}{4}\)