AP: 3, 7, 11, ..., can we find directly $a_{30} * a_{20}$ without actually finding $a_{30}$ and $a_{20}$ ? If yes find the product.
If true then enter $1$ and if false then enter $0$

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Solution

Here first term $a = 3$ and common difference $d = 4$ .
$a_{30} \times a_{20} = (a + 29 d) \times (a + 19 d)$
$= (3 + 29 \times 4) \times (3 + 19 \times 4)$
$= 119 \times 79 = 9401$
Yes. We can find $a_{30} \times a_{20}$ without actually finding $a_{30}, a_{20}$

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