waecmaths question:
The fourth term of an Arithmetic progression (A.P) is 37 and the first term is −20. Find the common difference
Option A:
63
Option B:
57
Option C:
19
Option D:
17
waecmaths solution:
$\begin{align} & a=-20,\text{ }{{T}_{4}}=37 \\ & {{T}_{n}}=a+(n-1)d \\ & {{T}_{4}}=a+(4-1)d=a+3d \\ & {{T}_{4}}=a+3d \\ & 37=-20+3d \\ & 3d=57 \\ & d=\frac{57}{3}=19 \\ & \text{The common difference is 19} \\\end{align}$
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