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NCERT EXERCISE 9.4 |

Find the sum to n terms of each of the series in Exercises 1 to 7.

**Question 1.** 1\times2+2\times3+3\times4+4\times5+…

**Question 2.** 1\times2\times3+2\times3\times4+3\times4\times5+…

**Question 3.** 3\times1^2+5\times2^2+7\times3^2+…

**Question 4.** \frac{1}{1\times2}+\frac{1}{2\times3}+\frac{1}{3\times4}+…

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NCERT EXERCISE 9.4 |

Find the sum to *n* terms of each of the series in Exercises 1 to 7.

**Question 5.** 5^2+6^2+7^2+…+20^2

**Question 6.** 3\times8+6\times11+9\times14+…

**Question 7.** 1^2+(1^2+2^2)+(1^2+2^2+3^2)+…

Find the sum to n terms of the series in Exercises 8 to 10 whose *n*^{th} terms is given by

**Question 8.** n(n+1)(n+4)

**Question 9.** n^2+2^n

**Question 10.** (2n-1)^2