(a) `log_2.17(5x-1)-log_2.17(x+7)=0`
Since the two logarithms have same base, express the right side as one logarithm.To do so, apply the quotient rule` log_b(M/N)=log_bM-log_bN` .
`log_2.17[(5x-1)/(x+7)]=0`
Then, convert to it to exponential equation. The equivalent exponential equation of `log_b M=a` is
`b^a=M` .
`2.17^0=(5x-1)/(x+7)`
`1=(5x-1)/(x+7)`
Now that the equation has no more logarithm, proceed to solve for x.
`(x+7)*1=(5x-1)/(x+7)*(x+7)`
`x+7=5x-1`
`x-x+7+1=5x-x-1+1`
`8=4x`
`8/4=(4x)/4`
`2=x`
Hence, the solution to the given equation is `x=2` .
(b) `2e^x+2=5`
First, isolate e^x.
`2e^x+2-2=5-2`
`2e^x=3`
`(2e^x)/2=3/2`
`e^x=3/2`
To remove the x in the exponent, take the logarithm of both sides.
`ln(e^x)=ln(3/2)`
`x ln e=ln(3/2)`
`x=ln(3/2)`
Hence, the solution to the equation is `x=ln (3/2)` .
(c) `5+2ln(x)=4`
First, isolate lnx.
`5-5+2lnx=4-5`
`2lnx=-1`
`lnx=-1/2`
Then, convert to its equivalent exponential equation.
`e^(-1/2)=x`
`1/e^(1/2)=x`
Hence, the solution to the equation is `x=1/e^(1/2)` .
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