How many term of the A.P. 15 , 12, 9 ., - are needed to give the sum 15 ? Explain the duble answer .

Explanation

To solve the problem of how many terms of the arithmetic progression (A.P.) 15, 12, 9, ... are needed to give the sum of 15, we will follow these steps:

### Step 1: Identify the first term and common difference
The first term \( a \) of the A.P. is 15, and the common difference \( d \) can be calculated as:
\[ d = 12 - 15 = -3 \]

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