Linearisation and Conversion to Linear Form
To Linearize a non-linear equation involving two variables \(x\) and \(y\),
\(Y = mX + c\).
Take note:
• \(Y\) can be a function of \(x\) and/or \(y\); similarly \(X\) can be a function of \(x\) and/or \(y\).
• \(m\) and \(c\) are constants and cannot contain \(x\) or \(y\).
• There may be more than 1 way to linearize an equation.
Divide or multiply both sides of the equation until it matches \(Y=mX+c\): one variable expression on the left, a constant multiple of another variable expression plus a constant on the right.
Algebraic conversions
| Given equation | Rearranged form | Plot (\(Y\) against \(X\)) | Gradient and intercept |
|---|---|---|---|
| \(y=ax^2+bx\) | |||
| \(y=ax^2+bx\) | |||
| \(y=a+\dfrac{b}{x}\) | |||
| \(y=ax+\dfrac{b}{x}\) |
More than one conversion can work for the same equation — the first two rows straighten the same law onto different axes. Always use the variables named on the axes in the question.
After converting, check the gradient and the intercept: if either still contains \(x\) or \(y\), the conversion is wrong.
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