do u mean 5^x = 25^ (x-1) or 5^x = 25^x -1. you need to express clearly.
if 5^x = 25^(x -1)
5^x = 5^(2x-2)
take log on both sides,
log 5^x = log 5^ (2x-2)
x log5 = 2x-2 log5, { ust log a^b= b loga }
we leave out log 5, then ,we get
x = 2x -2
2 = x,
x =2
2006-09-25 16:00:18
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answer #1
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answered by free aung san su kyi forthwith 2
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Q: Is it 5^x = 25^ (x-1) OR 5^x = 25^x -1 ?
If it's 5^x = 25^(x-1), you simply express 25 as 25 = 5^2.
by Law of Exponents which says (u^a)^b = u^(ab),
5^x = 5^[2(x-1)]
recall: if u^a = u^b , then a = b.
Thus, x = 2(x-1).
Solving for x, x = 2.
let's check it out: if x = 2, 5^x = 5^2 = 25.
25^(x-1) = 25^(2-1) = 25^1 = 25.
Clearly, 5^x = 25^(x-1) when x = 2.
2006-09-25 16:26:19
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answer #2
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answered by Hanz 2
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logarithm the two section xln19=ln143 x=ln143/ln19 use your calculator 2. 2^x=z z^2+z-12=0 (z+4)(z-3)=0 z= -4 z=3 2^x= -4 no answer 2^x=3 x=ln3/ln2 use your calculator 3. x-7=5^2 x=25+7=32 4. x^3=one hundred twenty 5 x=5 5. 5( x-2)=one hundred x-2=20 x=22
2016-12-15 14:25:20
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answer #3
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answered by vanpelt 4
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let a=5^x
so 5^x=25^x-1 becomes a=a^2-1
or a^2-a-1=0 the positive solution is a=(1+sqr(5))/2 = 5^x
so taking logs gives x=0.298994
2006-09-26 01:32:46
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answer #4
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answered by deflagrated 4
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5^x = 25^(x - 1)
5^x = (5^2)^(x - 1)
5^x = 5^(2(x - 1))
5^x = 5^(2x - 2)
therefore
x = 2x - 2
-x = -2
x = 2
ANS : x = 2
2006-09-25 16:39:43
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answer #5
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answered by Sherman81 6
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5^x = 25^(x-1)
5^x = (5^2)^(x-1)
5^x = 5^(2(x-1))
5^x = 5^(2x-2)
x = 2x-2
x = 2
2006-09-25 15:58:38
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answer #6
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answered by johnny m 2
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If, on the other hand, folks, you take the equation EXACTLY as written (and ammended) thus making it
5^x = 25^x - 1
the answer will come out approximately 0.2516 by iteration, since there is no closed form solution Im aware of........
2006-09-25 16:16:02
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answer #7
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answered by Steve 7
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x = 2
5^2= 25
25 ^(2-1) = 25
2006-09-25 15:58:06
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answer #8
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answered by Eric F 3
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5^x = 25^x-1
5^x = 5^2(x-1)
x=2x-1
-1x= -1
x=1
2006-09-25 15:50:32
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answer #9
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answered by Kaitlyn 4
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