Science (English Medium) Class 11 - CBSE Question Bank Solutions

Find the sum to indicated number of terms of the geometric progressions `sqrt7, sqrt21,3sqrt7`...n terms.

Find the sum to indicated number of terms in the geometric progressions 1, – a, a², – a³, ... n terms (if a ≠ – 1).

Find the sum to indicated number of terms in the geometric progressions x³, x⁵, x⁷, ... n terms (if x ≠ ± 1).

Evaluate `sum_(k=1)^11 (2+3^k )`

The sum of first three terms of a G.P. is  `39/10` and their product is 1. Find the common ratio and the terms.

The sum of first three terms of a G.P. is 16 and the sum of the next three terms is 128. Determine the first term, the common ratio and the sum to n terms of the G.P.

Find the sum of the products of the corresponding terms of the sequences `2, 4, 8, 16, 32 and 128, 32, 8, 2, 1/2`

Show that the products of the corresponding terms of the sequences a, ar, ar², …ar^{n – 1} and A, AR, AR², … `AR^(n-1)` form a G.P, and find the common ratio

Find four numbers forming a geometric progression in which third term is greater than the first term by 9, and the second term is greater than the 4^th by 18.

If the p^th, q^th and r^th terms of a G.P. are a, b and c, respectively. Prove that `a^(q - r) b^(r-p) c^(p-q) = 1`.

If the first and the n^th term of a G.P. are a ad b, respectively, and if P is the product of n terms, prove that P² = (ab)ⁿ.

If a, b, c and d are in G.P. show that (a² + b² + c²) (b² + c² + d²) = (ab + bc + cd)² .

Find the value of n so that  `(a^(n+1) + b^(n+1))/(a^n + b^n)` may be the geometric mean between a and b.