5.
If nth term of an A.P., is tn = (n-1)(n-2), then find the second term
9. a, b, c, d are in A.P. In which progression ka, kb, kc, kd belongs to?
10. If x, y, z are in A.P. Then what is the value of y?
ime
11. Write the formula to find the sum of first n terms of an A.P. and explain each term in it.
13. What is the value of 1 + 2+ 3+ 4 + ...n
15. If the sum of first n terms is 2n + 3n2, find an
17. Write the formula to find the nth term of a G.P. and explain each term in it.
18. Write G.P., if a = 256, r=-1/2
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Answer:
11.sn=n/2(2a+(n-1))d
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