Find the 7th term of the arithmetic progression whose first term is $5$ and common difference is $4$ .

easy 1 mark Class 10 · Mathematics · Arithmetic Progressions

Answer

29

The correct answer is $29$ — Thus the 7th term is $29$ .

Step-by-step solution

$T_{n} = a + (n - 1) d$ for the $n$ th term of an AP, where $a$ is the first term and $d$ is the common difference.
Substitute $n = 7$ , $a = 5$ and $d = 4$ to get $T_{7} = 5 + (7 - 1) \times 4$ .
$T_{7} = 5 + 6 \times 4 = 5 + 24 = 29$ .
Thus the 7th term is $29$ .

Common mistake: Forgetting to subtract 1 from the term number when using the formula

Concept tested: Find nth term of an AP