Arithmetic Progressions
CH05 Question Bank
CBSE_CH05_QUESTION_BANK
Grade 10
Question:
Is $-150$ a term of the AP $11, 8, 5, 2, \ldots$?
Step-by-Step Solution
Key Concept: Set the nth term equal to -150 and check whether n comes out as a positive integer.
$a=11,d=-3$. $a_n=11+(n-1)(-3)=-150\Rightarrow(n-1)(-3)=-161\Rightarrow n-1=\dfrac{161}{3}$. [1.0 Mark]
Since $\dfrac{161}{3}$ is not a whole number, $n$ is not a positive integer, so $-150$ is NOT a term of this AP. [1.0 Mark]
Correct Answer:
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