Bukit Panjang 2010 P1 Q3a Logarithm Question Solution (A Maths Tuition)

Question:
Solve the following equation:

(a) $5^{2x}-7^x-35(5^{2x})+36(7^x)=0$

Solution:

$-34(5^{2x})+35(7^x)=0$

$35(7^x)=34(5^{2x})$

Ln both sides, we get

$\ln 35 + x\ln 7=\ln 34+2x\ln 5$

$\ln 35-\ln 34=x(2\ln 5-\ln 7)$

$\displaystyle \boxed{x=\frac{\ln 35-\ln 34}{2\ln 5-\ln 7}=0.0228}$

Author: mathtuition88

Enter your comment here...

Fill in your details below or click an icon to log in:

Email (required) (Address never made public)

Name (required)

Website

You are commenting using your WordPress.com account. ( Log Out / Change )

You are commenting using your Facebook account. ( Log Out / Change )

Connecting to %s

%d bloggers like this: