Question 769901: 1) solve; log 7- log 70
2) /2x-1/ = /4x+3/
3)√x+1 – 3x = 1
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! 1) solve; log 7- log 70
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log(7/70) = log(1/10) = -1
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2) /2x-1/ = /4x+3/
2x-1 = 4x+3 or 2x-1 = -4x-3
2x = -4 or 6x = -2
x = -2 or x = -1/3
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3)√(x+1) – 3x = 1
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sqrt(x+1) = 3x+1
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Square both sides to get:
x+1 = 9x^2 + 6x + 1
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9x^2 + 5x = 0
x(9x+5) = 0
x = 0 or x = -5/9
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Checking frextraneous roots::
x = 0 ??
sqrt(0+1) - 3*0 = 1
1 - 0 = 1
1 = 1
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x = -5/9 ??
sqrt((-5/9)+1) -3(-5/9) = 1
sqrt(4/9) + 5/3 = 1
2/3 +5/3 = 1
7/3 = 1
Extraneous.
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Solution:: x = 0
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Cheers,
Stan H.
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