Solve: 2 In 3 = In(x-4)

1 answer:

5 0

$\bf \begin{array}{llll} \textit{Logarithm of rationals} \\\\ \log_a\left( \frac{x}{y}\right)\implies \log_a(x)-\log_a(y) \end{array}~\hfill \begin{array}{llll} \textit{Logarithm Cancellation Rules} \\\\ log_a a^x = x\qquad \qquad \stackrel{\textit{we'll use this one}}{a^{log_a x}=x} \end{array} \\\\[-0.35em] \rule{34em}{0.25pt}$

$\bf 2\ln(3)=\ln(x-4)\implies \ln(3^2)=\ln(x-4)\implies \ln(9)=\ln(x-4) \\\\\\ \log_e(9)=\log_e(x-4)\implies e^{\log_e(9)}=e^{\log_e(x-4)}\implies 9=x-4\implies \boxed{13=x}$

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6 labour complete a work in 12 days. How many labours should added to complete the works in 8 days?

mario62 [17]

Answer:

9 labours

Step-by-step explanation:

In order to solve this, we must know which kind of proportionality is this. There are two types of proportions, direct and indirect/inverse proportions. In direct proportion, if one quantity increases, the other quantity also increases.

In indirect proportion, if one quantity increases, the other decreases and vice versa.

As per this question, we know if the number of labour increases, the number of days to complete a work decreases, thus proving that this is an indirect/inverse proportion.

6 labours => 12 days

x labours => 8 days

Since its an inverse proprotion, multiply 6 with 12, and x with 8.

8x = 6 × 12

x = $\frac{6*12}{8}$