Arithmetic and Geometric Progressions — Mathematics STD 10 — Question
ICSE BoardEnglish MediumSTD 10MathematicsArithmetic and Geometric Progressions2 Marks
Question
Which term of the A.P. 53, 48, 43,… is the first negative term?
✓
Answer
Let $n$th term is the first negative term of the A.P. $53,48,43, \ldots$ Here, $a=53, d=48-53=-5$ $ \begin{aligned} & \therefore T_n=a+(n-1) d \\ & =53+(n-1) \times(-5) \\ & =53-5 n+5 \\ & =58-5 n \end{aligned} $ $ \begin{aligned} & 5 n=58 \\ & n=\frac{58}{5} \\ & =11 \frac{3}{5} \end{aligned} $ $\therefore 12$ th term will be negative.
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.