Question

If the first term of an A.P. is -5 and the common difference is 2 then the sum of the first 6 terms is (i) 0 (ii) 5 (iii) 6 (iv) 15

Answer 1

Given ,

• First term (a) = -5
• Common difference (d) = 2

We know that , the sum of first n terms of an AP is given by

$\boxed{ \sf{S_{n} = \frac{n}{2} \{2a + (n - 1)d \}}}$

Thus ,

$\sf \mapsto S_{6} =\frac{6}{2} \{2( - 5) + (6 - 1)2 \} \\ \\ \sf \mapsto S_{6} = 3 \{ - 10 + 10 \} \\ \\\sf \mapsto S_{6} = 0$

$\sf \therefore \underline{The \: sum \: of \: first \: 6 \: term \: of \: given \: AP \: is \: 0 }$