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1.
a. (x - 12,5) : 3/4 = 8/5
x - 12,5 = 8/5 x 3/4
x = 6/5 + 12,5
x = 137/10 = 13.7
1.
b, (x -2/5) x 5/11 = 75/22
x - 2/5 = 75/22 : 5/11
x = 15/2 + 2/5
x = 79/10 = 7.9
\(\dfrac{22}{5}\times\dfrac{6}{121}\times\dfrac{11}{4}\times\dfrac{3}{5}\times\dfrac{1}{3}\times\dfrac{5}{4}\)
\(=\left(\dfrac{22}{5}\times\dfrac{5}{4}\right)\times\left(\dfrac{6}{121}\times\dfrac{11}{4}\right)\times\left(\dfrac{3}{5}\times\dfrac{1}{3}\right)\)
\(=\dfrac{11}{2}\times\dfrac{3}{22}\times\dfrac{1}{5}\)
\(=\dfrac{3}{20}\)
\(=\dfrac{22\times6\times11\times3\times1\times5}{5\times121\times4\times5\times3\times4}=\dfrac{11\times2\times6\times11\times1}{11\times11\times4\times5\times4}=\dfrac{2\times6\times1}{4\times5\times4}=\dfrac{18}{100}=\dfrac{9}{50}\)
a.(x+2)+(x+5)+(x+8)+(x+11)+(x+14)=75
=>(x+x+x+x+x)+(2+5+8+11+14)=75
=>Xx5+40=75
=>Xx5=75-40
=>Xx5=35
=>x=35:5
=>x=7
a x+\(\frac{1}{2}\)=\(\frac{5}{7}\)
x=\(\frac{5}{7}\)-\(\frac{1}{2}\)
x=\(\frac{3}{14}\)
b \(\frac{25}{7}\)-x=\(\frac{8}{9}\)
x=\(\frac{25}{7}\)-\(\frac{8}{9}\)
x=\(\frac{169}{43}\)
c \(\frac{15}{11}\)*x=\(\frac{5}{3}\)
x=\(\frac{5}{3}\):\(\frac{15}{11}\)
x=\(\frac{11}{9}\)
D x*\(\frac{5}{12}\)=\(\frac{8}{9}\)
x=\(\frac{8}{9}\):\(\frac{5}{12}\)
x=\(\frac{32}{15}\)
a) \(x+\frac{1}{2}=\frac{5}{7}\)
\(x=\frac{5}{7}-\frac{1}{2}\)
\(x=\frac{10}{14}-\frac{7}{14}\)
\(x=\frac{3}{14}\)
b) \(\frac{25}{7}-x=\frac{8}{9}\)
\(x=\frac{25}{7}-\frac{8}{9}\)
\(x=\frac{225}{63}-\frac{56}{63}\)
\(x=\frac{169}{63}\)
c) \(\frac{15}{11}\cdot x=\frac{5}{3}\)
\(x=\frac{5}{3}:\frac{15}{11}\)
\(x=\frac{5}{3}\cdot\frac{11}{15}\)
\(x=\frac{11}{9}\)
d) \(x\cdot\frac{5}{12}=\frac{8}{9}\)
\(x=\frac{8}{9}:\frac{5}{12}\)
\(x=\frac{8}{9}\cdot\frac{12}{5}\)
\(x=\frac{32}{15}\)
a, 3/4 ÷ x/6 = 0,75
x/6 = 0,75 ÷ 0,75
x/6 = 1
=> x = 6
Vậy x = 6
b, 2,5 . 45/ x = 5/6
45/x = 5/6 ÷ 2,5
45/x = 1/3
=> x = 45 × 3
=> x = 135
Vậy x = 135
c, x/12 + 121,5 = 121,5
x/12 = 121,5 - 121,5
x/12 = 0
=> x = 0
Vậy x = 0
e, 6/8 = 15/x
3/4 = 15/x
=> x = 20
Vậy x = 20
Bài 2:
a, \(\dfrac{5}{23}\) \(\times\) \(\dfrac{17}{26}\) + \(\dfrac{5}{23}\) \(\times\) \(\dfrac{9}{26}\)
= \(\dfrac{5}{23}\) \(\times\) ( \(\dfrac{17}{26}\) + \(\dfrac{9}{26}\))
= \(\dfrac{5}{23}\) \(\times\) \(\dfrac{26}{26}\)
= \(\dfrac{5}{23}\)
b, \(\dfrac{3}{4}\) \(\times\) \(\dfrac{7}{9}\) + \(\dfrac{7}{4}\) \(\times\) \(\dfrac{3}{9}\)
= \(\dfrac{7}{12}\) + \(\dfrac{7}{12}\)
= \(\dfrac{14}{12}\)
= \(\dfrac{7}{6}\)
\(\frac{15}{8}\)+\(\frac{7}{12}\)-\(\frac{13}{3}\)x\(\frac{3}{8}\)
=\(\frac{45}{24}\)+\(\frac{14}{24}\)-\(\frac{13}{8}\)
=\(\frac{59}{24}\)-\(\frac{39}{24}\)
=\(\frac{20}{24}\)=\(\frac{5}{6}\)
\(\frac{11}{5}\)+\(\frac{5}{22}\):2+\(\frac{5}{6}\)
=\(\frac{11}{5}\)+\(\frac{5}{44}\)+\(\frac{5}{6}\)
=\(\frac{484}{220}\)+\(\frac{25}{220}\)+\(\frac{5}{6}\)
=\(\frac{509}{220}\)+\(\frac{5}{6}\)
=\(\frac{1527}{660}\)+\(\frac{550}{660}\)
=\(\frac{2077}{660}\)
a) 4/9.x=25/18:2/3
4/9.x=25/18.3/2
4/9.x=75/36
x=75/36:4/9
x=75/36x4/9
x=675/144
b)x:4/5=25/8:5/4
x:4/5=25/8x4/5
x:4/5=100/40
x:4/5=5/2
x=5/2x4/5
x=20/10
x=2/1=2
c)22/5:x=44/5:5/2
22/5:x=44/5x2/5
22/5:x=88/25
x=88/25:22/5
x=88/25x22/5
x=440/550
x=4/5
h nk
\(\left(x-12,5\right):\frac{3}{4}=\frac{8}{5}\)
\(x-12,5=\frac{8}{5}.\frac{3}{4}\)
\(x-12,5=\frac{6}{5}\)
\(x=\frac{6}{5}+12,5\)
\(x=\frac{137}{10}\)
\(\left(x-\frac{2}{5}\right)\times\frac{5}{11}=\frac{75}{22}\)
\(x-\frac{2}{5}=\frac{75}{22}:\frac{5}{11}\)
\(x-\frac{2}{5}=\frac{15}{2}\)
\(x=\frac{15}{2}+\frac{2}{5}\)
\(x=\frac{79}{10}\)