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\(\left(\dfrac{1}{2}+1\right)\times\left(\dfrac{1}{3}+1\right)\times\left(\dfrac{1}{4}+1\right)\times\left(\dfrac{1}{5}+1\right)\times\left(\dfrac{1}{6}+1\right)\)
\(=\dfrac{3}{2}\times\dfrac{4}{3}\times\dfrac{5}{4}\times\dfrac{6}{5}\times\dfrac{7}{6}\)
\(=\dfrac{3\times4\times5\times6\times7}{2\times3\times4\times5\times6}\)
\(=\dfrac{7}{2}\)
(
2
1
+1)×(
3
1
+1)×(
4
1
+1)×(
5
1
+1)×(
6
1
+1)
=
3
2
×
4
3
×
5
4
×
6
5
×
7
6
=
2
3
×
3
4
×
4
5
×
5
6
×
6
7
=
3
×
4
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5
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6
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7
2
×
3
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4
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5
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=
2×3×4×5×6
3×4×5×6×7
=
7
2
=
2
7
\(\dfrac{a}{27}-\dfrac{2}{9}=\dfrac{6}{18}\)
\(\dfrac{a}{27}=\dfrac{6}{18}+\dfrac{2}{9}\)
\(\dfrac{a}{27}=\dfrac{5}{9}\)
\(\dfrac{a}{27}=\dfrac{15}{27}\)
=> \(a=15\)
\(\dfrac{y}{20}-\dfrac{7}{12}=\dfrac{11}{30}\)
\(\dfrac{y}{20}=\dfrac{11}{30}+\dfrac{7}{12}\)
\(\dfrac{y}{20}=\dfrac{19}{20}\)
\(y\times20=19\times20\)
\(y\times20=380\)
\(y=19\)
\(\dfrac{y}{20}-\dfrac{7}{12}=\dfrac{11}{30}\)
\(\dfrac{y}{20}=\dfrac{11}{30}+\dfrac{7}{12}\)
\(\dfrac{y}{20}=\dfrac{22}{60}+\dfrac{35}{60}\)
\(\dfrac{y}{20}=\dfrac{57}{60}\)
\(y=\dfrac{57}{60}\times20\)
\(y=\dfrac{57}{3}\)
y =19
a \(\dfrac{3}{8}\times\dfrac{5}{2}+\dfrac{5}{8}\times\dfrac{5}{2}=\dfrac{5}{2}\left(\dfrac{3}{5}+\dfrac{5}{8}\right)=\dfrac{5}{2}\times\dfrac{8}{8}=\dfrac{5}{2}\times1=\dfrac{5}{2}\)
b \(33.12\times0=0\)
a 3/8 : 2/5 + 5,8 : 2/5
3/8 x 5/2 + 5,8 x 5/2
= 5/2 x ( 3/8 + 5.8)
= 5/2 x 6,175
= 247/16
nếu chỗ 5,8 bn ghi sai thì mik sửa đề thành 3/8 : 2/5 + 5/8 : 2/5
3/8 x 5/2 + 5/8 x 5/2
= 5/2 x ( 3/8 + 5/8)
= 5/2 x 1
=5/2
b (13,8 x 2,4 ) x (2,25 - 1,5 x 1,5 )
= 33.12 x 0
= 0
4 5/7 + 3,25 + 2/7 - 1/4
= 4 + 5/7 + 13/4 + 2/7 - 1/4
= 4 + (5/7 + 2/7) + (13/4 - 1/4)
= 4 + 1 + 3
= 8
Ta có:
\(\dfrac{5}{7}+3,25+\dfrac{2}{7}-\dfrac{1}{4}\)
\(=\left(\dfrac{5}{7}+\dfrac{2}{7}\right)+\left(3,25-0,25\right)\)
\(=\dfrac{7}{7}+3\)
\(=1+3\)
\(=4\)
Vậy: \(4=\dfrac{5}{7}+3,25-\dfrac{2}{7}-\dfrac{1}{4}\)
a) 5.(x-20) = 35
(x-20) = 35:5
x-20 = 7
x = 27
b) (x+125) -301 = 56
x+125 -301 = 56
x - 176 = 56
x = 56 +176
x= 232
c) 215 + (x-21):2 = 235
(x-21):2 = 235 - 215
(x-21):2 = 20
x-21 = 20 .2
x-21 = 40
x = 61
d) (x:23 +45) .67 = 8911
(x:23 +45) = 8911 : 67
x:23+45 = 133
x:23 = 133-45
x:23 = 88
x = 88.23
x = 2024
a) 5.(x - 20) = 35
⇒ x - 20 = 35 : 5
⇒ x - 20 = 7
⇒ x = 7 + 20
⇒ x = 27
b) (x + 125) - 301 = 56
⇒ x + 125 = 56 + 301
⇒ x + 125 = 357
⇒ x = 357 - 125
⇒ x = 232
c) 215 + (x - 21) : 2 = 235
⇒ (x - 21) : 2 = 235 - 215
⇒ (x - 21) : 2 = 20
⇒ x - 21 = 20 x 2
⇒ x - 21 = 40
⇒ x = 21 + 40
⇒ x = 61
d) (x : 23 + 45).67 = 8911
⇒ x : 23 + 45 = 8911 : 67
⇒ x : 23 + 45 = 133
⇒ x : 23 = 133 - 45
⇒ x : 23 = 88
⇒ x = 88 x 23
⇒ x = 2024
\(0=\left(x-5\right)^5-\left(x-5\right)^4\)
\(\left(x-5\right)^4\left(x-5-1\right)=0\)
\(\orbr{\begin{cases}\left(x-5\right)^4=0\\x-6=0\end{cases}}\)
\(\orbr{\begin{cases}x=5\\x=6\end{cases}}\)
a,
\(2^x=32\)
\(2^x=2^5\)
\(\Rightarrow x=5\)
b,
2x = 124
x = 62
c,
\(x^{15}-x=0\)
\(x\left(x^{14}-1\right)=0\)
\(\orbr{\begin{cases}x=0\\x^{14}-1=0\end{cases}}\)
\(\orbr{\begin{cases}x=0\\x=\pm1\end{cases}}\)
\(a\times2+a:2=5\)
\(a\times2+a\times\dfrac{1}{2}=5\)
\(a\times\left(2+\dfrac{1}{2}\right)=5\)
\(a\times\dfrac{5}{2}=5\)
\(a=5:\dfrac{5}{2}\)
\(a=2\)
Vậy \(a=2\)
\(2,25-\left(5\times a-125:5\right)=0\)
\(2,25-5\times a+25=0\)
\(27,25-5\times a=0\)
\(5\times a=27,25\)
\(a=27,25:5\)
\(a=5,45\)
Vậy a=5,45