12)[tex]\frac{{1000}^{x+2}}{{100}^{5x}}=\frac{{100}^{x-3}}{{1000}^{5-x}}\\\\\frac{{(10^3)}^{x+2}}{{(10^2)}^{5x}}=\frac{{(10^2)}^{x-3}}{{(10^3)}^{5-x}}\\\\\frac{{10}^{3x+6}}{{10}^{10x}}=\frac{{10}^{2x-6}}{{10}^{15-3x}}\\\\{10}^{3x+6-10x}={10}^{(2x-6)-(15-3x)}\\\\{10}^{-7x+6}=10^{5x-21}\\\\-7x+6=5x-21\\\\-7x-5x=-21-6\\\\-12x=-27\\\\x=\frac{-27}{-12}\\\\x=\frac{9}{4}[/tex]
13)
[tex]\frac{{32}^{4-x}}{{16}^{x+2}}=\frac{8^{5-x}}{32^{1-x}}\\\\\frac{{(2^5)}^{4-x}}{{(2^4)}^{x+2}}=\frac{{(2^3)}^{5-x}}{{(2^5)}^{1-x}}\\\\\frac{{2}^{20-5x}}{{2}^{4x+8}}=\frac{{2}^{15-3x}}{{2}^{5-5x}}\\\\2^{(20-5x)-(4x+8)}=2^{(15-3x)-(5-5x)}\\\\2^{12-9x}=2^{10+2x}\\\\12-9x=10+2x\\\\-9x-2x=10-12\\\\-11x=-2\\\\x=\frac{-11}{-2}\\\\x=\frac{11}2[/tex]
14)
[tex]12\times5^x+13\times5^x=625[/tex]
Misalkan, [tex]5^x=y[/tex]
[tex]12\times5^x+13\times5^x=625\\\\12y+13y=625\\\\25y=625\\\\y=\frac{625}{25}\\\\y=25[/tex]
Substitusi kembali y ke [tex]5^x[/tex]
[tex]y=25\\\\5^x=25\\\\5^x=5^2\\\\x=2[/tex]
15)
[tex]\frac{8\times3^x+7\times3^x}{3\times3^x+2\times3^x}=\frac19[/tex]
Misalkan, [tex]3^x=y[/tex]
[tex]\frac{8\times3^x+7\times3^x}{3\times3^x+2\times3^x}=\frac19\\\\\frac{8y+7y}{3y+2y}=\frac19\\\\\frac{15y}{5y}=\frac19\\\\\frac31=\frac19[/tex]
Dapat disimpulkan, bahwa soal no. 15 tidak memiliki solusi atau jawaban
(mungkin salah soal)
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12)
[tex]\frac{{1000}^{x+2}}{{100}^{5x}}=\frac{{100}^{x-3}}{{1000}^{5-x}}\\\\\frac{{(10^3)}^{x+2}}{{(10^2)}^{5x}}=\frac{{(10^2)}^{x-3}}{{(10^3)}^{5-x}}\\\\\frac{{10}^{3x+6}}{{10}^{10x}}=\frac{{10}^{2x-6}}{{10}^{15-3x}}\\\\{10}^{3x+6-10x}={10}^{(2x-6)-(15-3x)}\\\\{10}^{-7x+6}=10^{5x-21}\\\\-7x+6=5x-21\\\\-7x-5x=-21-6\\\\-12x=-27\\\\x=\frac{-27}{-12}\\\\x=\frac{9}{4}[/tex]
13)
[tex]\frac{{32}^{4-x}}{{16}^{x+2}}=\frac{8^{5-x}}{32^{1-x}}\\\\\frac{{(2^5)}^{4-x}}{{(2^4)}^{x+2}}=\frac{{(2^3)}^{5-x}}{{(2^5)}^{1-x}}\\\\\frac{{2}^{20-5x}}{{2}^{4x+8}}=\frac{{2}^{15-3x}}{{2}^{5-5x}}\\\\2^{(20-5x)-(4x+8)}=2^{(15-3x)-(5-5x)}\\\\2^{12-9x}=2^{10+2x}\\\\12-9x=10+2x\\\\-9x-2x=10-12\\\\-11x=-2\\\\x=\frac{-11}{-2}\\\\x=\frac{11}2[/tex]
14)
[tex]12\times5^x+13\times5^x=625[/tex]
Misalkan, [tex]5^x=y[/tex]
[tex]12\times5^x+13\times5^x=625\\\\12y+13y=625\\\\25y=625\\\\y=\frac{625}{25}\\\\y=25[/tex]
Substitusi kembali y ke [tex]5^x[/tex]
[tex]y=25\\\\5^x=25\\\\5^x=5^2\\\\x=2[/tex]
15)
[tex]\frac{8\times3^x+7\times3^x}{3\times3^x+2\times3^x}=\frac19[/tex]
Misalkan, [tex]3^x=y[/tex]
[tex]\frac{8\times3^x+7\times3^x}{3\times3^x+2\times3^x}=\frac19\\\\\frac{8y+7y}{3y+2y}=\frac19\\\\\frac{15y}{5y}=\frac19\\\\\frac31=\frac19[/tex]
Dapat disimpulkan, bahwa soal no. 15 tidak memiliki solusi atau jawaban
(mungkin salah soal)