# The 21st term of an AP whose first two terms are - 3 and 4, isA. 17B. 137C. 143D. - 143 first two terms of an AP are a = - 3 and a2 = 4.

As we know, nth term of an AP is

an = a + (n - 1)d

where a = first term

an is nth term

d is the common difference

a2 = a + d

4 = - 3 + d

d = 7

Common difference, d = 7

a21 = a + 20d

= - 3 + (20)(7)

= 137

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