giup minh
tinh bang cach thuan tien
7/9 x 5/16 : 5/9 x 4/7
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\(a,\dfrac{5}{9}\times\dfrac{5}{2}+\dfrac{4}{9}\times\dfrac{5}{2}=\dfrac{5}{2}\times\left(\dfrac{5}{9}+\dfrac{4}{9}\right)=\dfrac{5}{2}\times1=\dfrac{5}{2}\)
\(12\times\dfrac{3}{4}-\dfrac{3}{4}\times\dfrac{12}{7}=\dfrac{3}{4}\times\left(12-\dfrac{12}{7}\right)=\dfrac{3}{4}\times\dfrac{72}{7}=\dfrac{54}{7}\)
a) 3/5x7/9+11/9x3/5
=3/5 x(7/9+11/9)
= 3/5x2
=6/5
b)14/13:1/2+3/13x2-2x7/13
= 14/13 x 2 +3/13 x2 - 2x7/13
=2 x (14/13 +3/13 -7/13)
= 2 x 10/13
= 20/13
a) 3/5 x 7/9 + 11/9 x 3/5 - 3/10
= 3/5 x 7/9 + 11/9 x 3/5 - 3/5 x 2
= 3/5 x ( 7/9 + 11/9 - 2 )
= 3/5 x 0
= 0
b) 14/13 : 1/2 + 3/13 x 2 - 2 x 7/13
= 14/13 x 2/1 + 3/13 x 2 - 2 x 7/13
= ( 14/13 + 3/13 - 7/13 ) x 2
= 10/13 x 2 = 20/13
\(\frac{5}{9}:\frac{4}{7}+\frac{13}{9}\cdot\frac{7}{4}\)
\(=\frac{5}{9}\cdot\frac{7}{4}+\frac{13}{9}\cdot\frac{7}{4}\)
\(=\left(\frac{5}{9}+\frac{13}{9}\right)\cdot\frac{7}{4}\)
\(=2\cdot\frac{7}{4}\)
\(=\frac{14}{4}\)
=\(\frac{5}{9}\)*\(\frac{7}{4}\)+\(\frac{13}{9}\)*\(\frac{7}{4}\)
=\(\frac{7}{4}\)*(\(\frac{5}{9}+\frac{13}{9}\))
=\(\frac{7}{4}\)*2
=\(\frac{7}{2}\)
\(\frac{2}{9}+\frac{1}{5}+\frac{7}{9}+\frac{4}{5}=\left(\frac{2}{9}+\frac{7}{9}\right)+\left(\frac{1}{5}+\frac{4}{5}\right)=\frac{9}{9}+\frac{5}{5}=1+1=2\)
\(\frac{2}{9}+\frac{1}{5}+\frac{7}{9}+\frac{4}{5}=\left(\frac{2}{9}+\frac{7}{9}\right)+\left(\frac{1}{5}+\frac{4}{5}\right)=1+1=2\)
(x+5)+(x+6)+(x+7)+(x+8)=58
=> x+5+x+6+x+7+x+8=58
=> 4x+26=58
=> 4x=32
=> x=8
Vậy x=8
tk cho mk nha
(bn mới lớp 5 à ,thế thì dấu " =>" là dấu suy ra)
*****Chúc bạn học giỏi*****
7/9 x 5/16 : 5/9 x4/7
=7/9 x 5/16 x9/5 x 4/7
=7/9 x 45/80 x 4/7
=7/9 x 9/16 x 4/7
=7 x 9 x 4 /9 x 16 x 7
=1/4