Question 27

waecmaths question: 

Make b the subject of the relation$lb=\tfrac{1}{2}(a+b)h$

Option A: 

$\frac{ah}{2l-h}$

Option B: 

$\frac{2l-h}{al}$

Option C: 

$\frac{al}{2l-h}$

Option D: 

$\frac{al}{2-h}$

waecmaths solution: 

$\begin{align}  & lb=\tfrac{1}{2}(a+b)h \\ & 2lb=ah+bh \\ & 2lb-bh=ah \\ & b(2l-h)=ah \\ & b=\frac{ah}{2l-h} \\\end{align}$

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