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# For the following APs, write the first term and the common difference. (i) 3, 1, –1, –3 … (ii) –5, –1, 3, 7… (iii) $${{1}\over{3}},{{5}\over{3}},{{9}\over{3}},{{13}\over{3}}$$ (iv) 0.6, 1.7, 2.8, 3.9 …

(i) 3, 1, –1, –3…

First term = a = 3,
Common difference (d)
= Second term – first term
= Third term – second term
and so on

Therefore, Common difference (d) = 1 – 3 = –2

(ii) –5, –1, 3, 7…

First term = a = –5
Common difference (d)
= Second term – First term
= Third term – Second term
and so on

Therefore, Common difference (d)
= –1 – (–5) = –1 + 5 = 4

(iii)$${{1}\over{3}},{{5}\over{3}},{{9}\over{3}},{{13}\over{3}}$$

First term = a = $${{1}\over{3}}$$
Common difference (d)
= Second term – First term
= Third term – Second term
and so on

Therefore, Common difference (d)
= $${{5}\over{3}} - {{1}\over{3}} = {{4}\over{3}}$$

(iv) 0.6, 1.7, 2.8, 3.9…

First term = a = 0.6

Common difference (d)
= Second term – First term
= Third term – Second term and so on

Therefore, Common difference (d)
= 1.7 - 0.6 = 1.1