NCERT · Class 11 · Maths

Chapter 9: Sequences and Series Exercise 9.3

Practice each question, then open the answer or worked solution.

Questions

32 questions

Q31Written answer

What will Rs 500 amount to in 10 years after its deposit in a bank which pays an annual interest rate of 10% compounded annually?

Show solutionHide solution

Worked solution

Given,

The amount deposited in the bank is Rs 500.

At the end of first year, amount = Rs 500(1 + 1/10) = Rs 500 (1.1)

At the end of 2^nd year, amount = Rs 500 (1.1) (1.1)

At the end of 3^rd year, amount = Rs 500 (1.1) (1.1) (1.1) and so on….

Therefore,

The amount at the end of 10 years = Rs 500 (1.1) (1.1) … (10 times)

= Rs 500(1.1)¹⁰

Q32Written answer

If A.M. and G.M. of roots of a quadratic equation are 8 and 5, respectively, then obtain the quadratic equation.

Show solutionHide solution

Worked solution

Let’s consider the roots of the quadratic equation to be a and b.

Then, we have

NCERT Solutions Class 11 Mathematics Chapter 9 ex.9.3 - 41

We know that,

A quadratic equation can be formed as,

x²– x (Sum of roots) + (Product of roots) = 0

x² – x (a + b) + (ab) = 0

x² – 16x + 25 = 0 [Using (1) and (2)]

Therefore, the required quadratic equation is x² – 16x + 25 = 0

Showing 31 to 32 of 32 results