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\(1,\\ c,\dfrac{17}{6}-\dfrac{3}{7}-\dfrac{5}{6}=\dfrac{17\times7-3\times6-5\times7}{6\times7}=\dfrac{119-18-35}{42}=\dfrac{66}{42}=\dfrac{11}{7}\\ 2,\\ a,\dfrac{6}{9}+\dfrac{3}{15}+\dfrac{7}{15}\\ =\dfrac{6:3}{9:3}+\dfrac{7+3}{15}\\ =\dfrac{2}{3}+\dfrac{10}{15}\\ =\dfrac{2}{3}+\dfrac{2}{3}\\ =\dfrac{2+2}{3}=\dfrac{4}{3}\)
\(b,\dfrac{7}{2}+\dfrac{29}{12}-\dfrac{11}{12}\\ =\dfrac{7}{2}+\left(\dfrac{29}{12}-\dfrac{11}{12}\right)\\ =\dfrac{7}{2}+\dfrac{29-11}{12}\\ =\dfrac{7}{2}+\dfrac{18}{12}\\ =\dfrac{7}{2}+\dfrac{18:6}{12:6}\\ =\dfrac{7}{2}+\dfrac{3}{2}\\ =\dfrac{7+3}{2}=\dfrac{10}{2}=5\)
\(c,\dfrac{26}{25}-\dfrac{3}{5}-\dfrac{2}{5}\\ =\dfrac{26}{25}-\dfrac{3\times5}{5\times5}-\dfrac{2\times5}{5\times5}\\ =\dfrac{26-15-10}{25}\\ =\dfrac{1}{25}\)
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
a)
\(\left(x-\dfrac{2}{3}\right):\dfrac{1}{2}=\dfrac{5}{7}\)
\(\Rightarrow x-\dfrac{2}{3}=\dfrac{5}{7}\) x \(\dfrac{1}{2}\)
\(\Rightarrow x-\dfrac{2}{3}=\dfrac{5}{14}\)
\(\Rightarrow x=\dfrac{5}{14}+\dfrac{2}{3}\)
\(\Rightarrow x=\dfrac{15}{42}+\dfrac{2}{42}\)
\(\Rightarrow x=\dfrac{17}{42}\)
b)
\(x\) x \(\dfrac{1}{2}=1-\dfrac{1}{3}\)
\(x\) x \(\dfrac{1}{2}=\dfrac{3}{3}-\dfrac{1}{3}\)
\(x\) x \(\dfrac{1}{2}=\dfrac{2}{3}\)
\(\Rightarrow x=\dfrac{2}{3}:\dfrac{1}{2}\)
\(\Rightarrow x=\dfrac{2}{3}\) x \(2=\dfrac{4}{3}\)
c)
\(\dfrac{26}{5}-x=\dfrac{9}{15}\) x \(\dfrac{25}{3}\)
\(\dfrac{26}{5}-x=5\)
\(\Rightarrow x=\dfrac{26}{5}-5\)
\(\Rightarrow x=\dfrac{26}{5}-\dfrac{25}{5}\)
\(\Rightarrow x=\dfrac{1}{5}\)
73 x 46 + 27 x 46 = 46 x [ 73 +27 ] = 46 x 100 = 4600
84 x 312 + 18x 312 = 312 x[84+18]=312x 102 = 31824
15 x5 + 15 x6 -15 + 100 =150
DT hồ đó là
378x[378x3]= 428652 m vuông
Đ/S : 428652m vuông
73 x 46 + 27 x 46
= ( 73 + 27 ) x 46
= 100 x 46
= 4600
84 x 312 + 18 x 312
= ( 84 + 18 ) x 312
= 102 x 312
= 31824
15 x 5 + 15 x 6 - 15 + 100
= 15x ( 5 + 6 - 1 ) + 100
= 15 x 10 - 100
= 150 - 100
= 50
x : [ 9 x 6 ] = 4
x : 54 = 4
x = 4 x 54
x = 216
Bài 2 :
Chiều dài khu rừng là :
378 x 3 = 1134 ( m )
Diện tích khu rừng là :
378 x 1134 = 428652 (m2 )
Đáp số : 428652 m2
Lời giải đầy đủ:
Bài 3:tìm x
A,
6.(x+9845)=29042.6
(x+9845)=29042.6:6
x+9845=29042
x=29042-9845
x=19197.
B,
(x:3).8=8.3198
(x:3)=3198.8:8
x:3=3198
x=3198.3
x=9594.
Bài 7:
A/191+x+9=43.5
200+x=215
x=215-200
x=15.
B/x.25.4=125.8
x.100=1000
x=1000:100
x=10.
Bài 8:
A/ 128.x-12.x-16.x=5208000
(128-12-16).x=5208000
100.x=5208000
x=5208000:100
x=52080.
B/ x.27+x.30+x.43=210500
x.(27+30+43)=210500
x.100=210500
x=210500:100
x=2105.
K mình nhé!
( 12 x 13 + 14 x 15 + ... + 24 x 25 + 26 x 27 ) x ( 14 + 6 - 10 + 5 - 3 x 5 )
= ( 12 x 13 + 14 x 15 + ... + 24 x 25 + 26 x 27 ) x 0
= 0
\(a,\dfrac{x}{4}=\dfrac{15}{20}\\ \Rightarrow\dfrac{x}{4}=\dfrac{3}{4}\\ \Rightarrow x=3\\ b,\dfrac{15}{x}=\dfrac{25}{35}\\ \Rightarrow\dfrac{15}{x}=\dfrac{5}{7}\\ \Rightarrow\dfrac{15}{x}=\dfrac{15}{21}\\ \Rightarrow x=21\\ c,\dfrac{x}{5}=\dfrac{26}{65}\\ \Rightarrow\dfrac{x}{5}=\dfrac{2}{5}\\ \Rightarrow x=2\\ d,\dfrac{3}{x}=\dfrac{51}{85}\\ \Rightarrow\dfrac{3}{x}=\dfrac{3}{5}\\ \Rightarrow x=5\)
a,x4=1520⇒x4=34⇒x=3b,15x=2535⇒15x=57⇒15x=1521⇒x=21c,x5=2665⇒x5=25⇒x=2d,3x=5185⇒3x=35⇒x=5
\(\dfrac{26}{5}\) - x = \(\dfrac{9}{15}\) x \(\dfrac{25}{3}\)là x = 0,2