waecmaths question:
Adding 42 to a given positive number gives the same result as squaring the number. Find the number.
Option A:
14
Option B:
13
Option C:
7
Option D:
6
waecmaths solution:
$\begin{align} & \text{Let the positive number be }a \\ & 42+a={{a}^{2}} \\ & {{a}^{2}}-a-42=0 \\ & (a-7)(a+6)=0 \\ & a=7\text{ or }a=-6\text{ (Ignore }a=-6) \\ & a=7 \\\end{align}$
maths year:
maths topics: