Question

if an ap is 12 is -13 and the sum of first four terms is 24 what is the sum of first 10 term ​

Answer 1

Step-by-step explanation:

if the 1st term is a and common difference is b then a+11b= -13

again 4/2{2a+(4-1).b}=24

2.(2a +3b)=24

2a+3b=24/2=12

again 2a+22b= -26

subtracting, -19b=38

b= -2

then a= -13 +22=9

the sum of 1st 10 term

10/2{2.9+(10-1).(-2)}

5(18+9.(-2)}

=5(18-18)=5.0=0