Question

Two arithmetic progressions has the same common difference. If the first term
of the first progression is 3 and that of the other is 8, then the difference between
their 3rd term is
​

Answer 1

Step-by-step explanation:

For first A.P

S1n=(2n)(2n+(n−1)d)

S130=(230)(2×3+(30−1)d)

S130=15(6+29d)

S130=90+435d

For second AP

S2n=(2n)(2n+(n−1)d)

S230=(230)(2×8+(30−1)d)

S230=15(16+29d)

S230=240+435d

Difference between S130−S230=(90+435d)−(240+435d)=150