3x-1+5.3x-1=486
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\(a,5^x+5^{x+2}=650\\ \Rightarrow a,5^x+5^x.25=650\\ \Rightarrow26.5^x=650\\ \Rightarrow5^x=25\\ \Rightarrow5^x=5^2\\ \Rightarrow x=2\)
\(b,3^{x.1}+5.3^{x.1}=162\\ \Rightarrow3^x+5.3^x=162\\ \Rightarrow6.3^x=162\\ \Rightarrow3^x=27\\ \Rightarrow3^x=3^3\\ \Rightarrow x=3\)
\(2.3^x+5.3^x.3=153\Leftrightarrow2.3^x+15.3^x=153\)
\(\Leftrightarrow17.3^x=153\Leftrightarrow3^x=9\Leftrightarrow x=2\)
\(\Leftrightarrow2.3^x+5.3.3^x=153\)
\(\Leftrightarrow17.3^x=3^2.17\)
\(\Leftrightarrow3^x=3^2\Rightarrow x=2\)
2/5.3x-1/2-1/4=1/5
=>2/5.3x-1/4=1/5
=>2/5.3x=1/5+1/4
=>2/5.3x=9/20
=>3.x=9/20:2/5
=>3.x=9/8
=>x=9/8:3
=>x=3/8
vay x=3/8
2/5.3x-1/2-1/4 = 1/5
=> 2/5.3x = 1/5+1/4+1/2
2/5.3x = 19/20
3x = (19/20):(2/5)
3x = 19/8
x = (19/8):3
x = 19/24
Trả lời:
\(3x+1+5\times3x+2=144\)
\(\Leftrightarrow3x+1+15x+2=144\)
\(\Leftrightarrow18x=141\)
\(\Leftrightarrow x=\frac{47}{8}\)
Vậy \(x=\frac{47}{8}\)
\(B=5\cdot\left(2x-1\right)^2+4\cdot\left(x-1\right)\cdot\left(x+3\right)-2\cdot\left(5\cdot3x\right)\)
\(=5\left(4x^2-4x+1\right)+\left(4x-4\right)\cdot\left(x+3\right)-2\cdot15x\)
\(=20x^2-20x+5+4x^2+12x-4x-12-2\cdot15x\)
\(=20x^2-20x+5+4x^2+12x-4x+12-30x\)
\(=24x^2-42x-7\)
(B=5left(2x-1 ight)^2+4left(x-1 ight)left(x+3 ight)-2left(5.3x ight)=5left(4x^2-4x+1 ight)+4left(x^2-4x+3 ight)-30x=20x^2-20x+5+4x^2-16x+12-30x=24x^2-66x+17)
Theo đề ta có:
\(5.3^{3x+2}-27^{x+1}=486\)
\(\Rightarrow5.27^x.9-27^x.27=486\)
\(\Rightarrow27^x\left(45-27\right)=486\)
\(\Rightarrow27^x.18=486\)
\(\Rightarrow27^x=\frac{486}{18}\)
\(\Rightarrow27^x=27\)
\(\Rightarrow27^x=27^1\)
\(\Rightarrow x=1\)
vậy \(x=1\)
\(3^x\cdot3^{x+1}\cdot18=486\)
\(\Leftrightarrow2x+1=3\)
hay x=1
3x-1 + 5 . 3x-1 = 486
3x-1 . ( 5 + 1 ) = 486
3x-1 . 6 = 486
3x-1 = 486 : 6
3x-1 = 81
3x-1 = 34
=> x - 1 = 4
x = 4 + 1
x = 5
Vậy x = 5
3x-1 + 5.3x-1 = 486
1.3x-1 + 5.3x-1 = 486
=> 3x-1.( 1 + 5) = 486
3x-1. 6 = 486
3x - 1 = 486 : 6
3 x - 1 = 81
3 x - 1 = 34
=> x - 1 = 4
x = 4 + 1
x = 5
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