logarithmic inequalities

diff --git a/methods/stuff.md b/methods/stuff.md
index 1eb560c269db297415fbaa3cd358a93f56666691..addaf9b2a57959320e9d7f040c5471fb540c4e63 100644 (file)
--- a/methods/stuff.md
+++ b/methods/stuff.md
@@ -15,3 +15,12 @@ $^n\sqrt{x}=x^{1/n}$
 ## Logarithms
 
 $$\log_b (x) = n \quad \operatorname{where} \hspace{0.5em} b^n=x$$
+
+## Using logs to solve index eq's
+
+Used for equations without common base exponent
+
+Or change base:  
+$$\log_b c = {{\log_a c} \over {\log_a b}}$$
+
+If $a<1, \quad \log_{b} a < 0$ (flip inequality operator)
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