Question

in an ap first term is -4 the last term is 29 and the sum of all its terms is 150. Find its common difference

Answer 1

a=-4
an=29
Sn=150
Sn=ñ/2(a+an)
150=ñ/2(-4+29)
150=ñ/2(25)
150×2=25n
300=25n
ñ=300/25
ñ=12