Log-linear transformation

Log-linear transformation係DSE Maths Core好鍾意問嘅類型，可以話年年都有一條，MC同埋長題目(Section B)都問過。睇落好似好複雜，不過只要明白個操作，就會覺得好簡單。覺得難係因為書係完完全全冇教到。

By definition, log-linear transformation is the process of transforming function [exponential function (y=ab^x) or power function (y=axⁿ)] into linear form by taking log.

簡單D講，log-linear transformation有兩個type(case)

Type 1 (Case 1): y=ab^x

Type 2 (Case 2): y=axⁿ

個操作就係將左右take log, 之後將條式變到好似Equation of a Straight Line 咁。

首先你要知道咩係Equation of a Straight Line。在x-y coordinate plane 上嘅直線，都可以以Equation of a Straight Line（直線方程）去表達。

一般就係y=mx+c

‘y’: y-axis 表達嘅野

m: slope

‘x’: x-axis 表達嘅野

c: y-intercept

Type 1 (Case 1): y=ab^x

Type 2 (Case 2): y=axⁿ

你會係幅圖搵到你要嘅野，例如slope/y-int. 有時會唔俾式你,要你由幅圖有嘅搵番條式。有時個log base唔係10，又可能直情俾兩個唔同嘅log base。當遇到就諗下啦。

DSE Past Paper

HKDSE 2012 Paper II Q32

HKDSE 2013 Paper II Q32