Question

If nth term of an AP is 1 - 5n, then find the common difference

Answer 1

Step-by-step explanation:

1 - 5n

put n = 1 to get first term

1 - 5×1 => -4 => a1

put n = 2 to get 2nd term

1 - 5×2 => -9 => a2

d = a2 - a1 => -9 -(-4) => -9 + 4 => - 5

Answer 2

$Given \: n^{th} \: term \: of \: an \: A.P :$

$a_{n} = 1 - 5n$

$1) If \: n = 1 \: then \: a_{1} = 1 - 5 \times 1 \\= 1 - 5 \\= -4$

$2) If \: n = 2\: then \: a_{2} = 1 - 5 \times 2 \\= 1 - 10 \\= -9$

$Now , \red{ Common \: difference (d) } \\= a_{2} - a_{1} \\= -9 - (-4) \\= -9 + 4 \\= -5$

Therefore.,

$\red{ Required \: common \: difference } \\\green { = -5 }$

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