Jambmaths question:
If $y={{(1+x)}^{2}},$find $\frac{dy}{dx}$
Option A:
2x+2
Option B:
1+2x
Option C:
2x -1
Option D:
x -1
Jamb Maths Solution:
$\begin{align} & y={{(1+x)}^{2}} \\ & \text{Using the chain or composite rule} \\ & \text{Let }u=1+x \\ & y={{u}^{2}} \\ & \frac{dy}{du}=2u \\ & \frac{du}{dx}=1 \\ & \frac{dy}{dx}=\frac{dy}{du}\times \frac{du}{dx}=2u\times 1 \\ & \frac{dy}{dx}=2u=2(1+x) \\ & \frac{dy}{dx}=2+2x \\\end{align}$
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