Question

in an ap if the 12th term is -13 and the sum of its first four terms is 24 find the sum of its first 10 terms

Answer 1

✨✨ Hola ✨✨

your solution ✔✔✔✔✔✔✔✔

Answer 2

mate A/Q

A12= -13

a+11d=-13 -----------(1)

now again A/Q

a1+a2+a3+a4=24

a+a+d+a+2d+a+3d=24

4a+6d=24-----------(2)

multiplying equation 1 by 4 and equation 2 by 1 and subtract equation 2 from 1 we get...

(a+11d= -13)4

(4a+6d= 24)1

4a+44d= -52

4a+6d =24

(-). (-). (-)

-----------------------

-38d= -76a

d=2

put d=2 in equation 1 we get

a+11d=-13

a+22=-13

a=-13-22

a=-35

S10= n/2(2a+(n-1)d)

10/2(2(-35)+9d)

=5(-70+18)

= -104

hope it will helpful to you