Question

Sum of 1st 11 terms if ap is -3,-1/2, 2,...​

Answer 1

Step-by-step explanation:

for AP series of n terms we know that sum is given by -

S(sum) = n/2{2a+(n-1) *d}

were a is the first term and d is the common difference of second term and first term.

now here in this series a1 = -3 and a2 = -1/2

d = a2-a1

= -1/2 - (-3)

= -1/2+3

= 5/2

and n= 11 (first 11 terms in the series)

S = 11/2{2*(-3) + (11-1) * 5/3}

= 11/2{(-6+10)*5/3}

= 11/2(4*5/3)

= 11/2*20/3

= 110/3