tìm a/b biết:
a/b *3/5 =1/5+2/3
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a) \(x+1^3=2^5-\left(-1^3\right)\)
\(\Rightarrow x+1=33\)
=> x = 32
b) \(3^7-x=1^4-\left(-3^5\right)\)
\(\Rightarrow2187-x=1+243=244\)
=> x = 1943
a) \(a:b=2\dfrac{2}{5}:\dfrac{4}{5}=\dfrac{12}{5}\cdot\dfrac{5}{4}=3:1\)
b) \(a:b=7.7:1.1=7:1\)
c) \(a:b=\dfrac{0.7\cdot100}{50}=\dfrac{70}{50}=\dfrac{7}{5}\)
d) \(a:b=\dfrac{3}{5}\cdot\dfrac{100}{120}=\dfrac{1}{2}\)
e) \(a:b=\dfrac{\dfrac{3}{2}\cdot60}{\dfrac{1}{2}}=3\cdot60=180:1\)
g) \(a=66\dfrac{2}{3}\%m=\dfrac{200}{3}\cdot\dfrac{1}{100}m=\dfrac{2}{3}m\)
\(b=0.5\%km=0.005km=5m\)
Do đó: \(a:b=\dfrac{2}{3}:5=\dfrac{2}{15}\)
a: =>1/3x-2/5x=5
=>-1/15x=5
=>x=-75
b: =>4x=4
=>x=1
c: =>6*3^x-5*3^x=243
=>3^x=243
=>x=5
1,
a, \(\left(\dfrac{-4}{3}+\dfrac{1}{3}\right).\dfrac{5}{12}\)=-\(\dfrac{5}{12}\)
b, \(\dfrac{16}{5}+\left(\dfrac{-45}{14}\right):\dfrac{3}{28}\)
=\(\dfrac{-2}{15}\)
2,
a, 2x+19=25
=>x=3
b, \(-\dfrac{2}{9}x=\dfrac{1}{3}\)
=>x=\(\dfrac{-3}{2}\)
Bài 1:
a) Ta có: \(\dfrac{-4}{3}\cdot\dfrac{5}{12}+\dfrac{1}{3}\cdot\dfrac{5}{12}\)
\(=\dfrac{5}{12}\cdot\left(\dfrac{-4}{3}+\dfrac{1}{3}\right)\)
\(=\dfrac{-5}{12}\)
b) Ta có: \(3\dfrac{1}{5}+\left(\dfrac{2}{7}-\dfrac{7}{2}\right):\dfrac{3}{28}\)
\(=\dfrac{16}{5}+\left(\dfrac{4}{14}-\dfrac{49}{14}\right):\dfrac{3}{28}\)
\(=\dfrac{16}{5}+\dfrac{-45}{14}\cdot\dfrac{28}{3}\)
\(=\dfrac{16}{5}-30=\dfrac{-134}{5}\)
a: \(\Leftrightarrow2x+\dfrac{7}{2}=\dfrac{16}{3}:\dfrac{8}{3}=2\)
=>2x=-3/2
hay x=-3/4
b: 2x+3=5
=>2x=2
hay x=1
c: =>3(x-2)=4(5+x)
=>4x+20=3x-6
=>x=-26
a) \(-0,6x-\dfrac{7}{3}=5,4\Leftrightarrow-\dfrac{3}{5}x=5,4+\dfrac{7}{3}\Leftrightarrow x=\dfrac{116}{15}.\left(-\dfrac{5}{3}\right)=-\dfrac{116}{9}\).
b) \(2,8:\left(\dfrac{1}{5}-3x\right)=1\dfrac{2}{5}\Leftrightarrow\dfrac{1}{5}-3x=2,8:\dfrac{7}{5}\Leftrightarrow-3x=2-\dfrac{1}{5}\Leftrightarrow x=\dfrac{9}{5}:\left(-3\right)=-\dfrac{3}{5}\).
a) (x - 3)2 - 5.(x - 2) + 5 = 0.
<=> x^2 - 6x + 9 - 5x + 10 + 5 = 0
<=> x^2 - 11x + 24 = 0
<=> (x-3)(x-8)=0
<=> x = 3 hoặc x = 8
\(\frac{a}{b}\cdot\frac{3}{5}=\frac{1}{5}+\frac{2}{3}\)
=> \(\frac{a}{b}\cdot\frac{3}{5}=\frac{3}{15}+\frac{10}{15}=\frac{13}{15}\)
=> \(\frac{a}{b}=\frac{13}{15}:\frac{3}{5}=\frac{13}{15}\cdot\frac{5}{3}=\frac{13}{9}\)