6x^1,7+4=14

just a little info here.

In many countries a comma is used instead of a decimal point.  

Hard to answer this without knowing what you mean. Instead of a comma, should there be another sign of operation?

Assuming this is 

$$6x^{1.7}+4=14$$

subtract 4 from both sides

$$6x^{1.7}=10$$

divide by 6

$$x^{1.7}=\frac{10}{6}$$

Take logs of both sides and use the fact that log(a^b) = b*log(a) and log(a/b) = log(a) - log(b)

$$1.7\log{x}=\log{10}-\log{6}$$

divide by 1.7

$$\log{x}=\frac{\log{10}-\log{6}}{1.7}$$

Use the fact that log₁₀a = b means a = 10^b

$$x=10^{\frac{\log{10}-\log{6}}{1.7}}$$

and since log₁₀10 = 1

$$x=10^{\frac{1-\log{6}}{1.7}}$$

You can complete the calculation.

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