Rationalizing the Expressions for x and y

Oct 13, 2025 by wbrum.org 22 views

Q. Show that the following are rational. If x = √5 - √2 / √3 + √2 and y = √3 + √2 / √3 - √2 . Find the value of x (i) x²-y²(ii) x² + 2xy + y ²(iii) x²+ xy+y²(iv) x²+y² for class 9 maths bosem. Chapter no 1 " Number System "

In this article, we will be dealing with a problem from the chapter "Number System" of class 9 maths bosem. The problem involves finding the value of certain expressions involving the variables x and y, which are defined in terms of square roots. We will start by rationalizing the expressions for x and y, and then use these rationalized expressions to find the values of the given expressions.

Rationalizing the Expressions for x and y

First, let's rationalize the expressions for x and y.

Rationalizing the Expression for x

We have x = (√5 - √2) / (√3 + √2). To rationalize this expression, we multiply both the numerator and denominator by the conjugate of the denominator, which is (√3 - √2).

import sympy as sp

# Define the variables
x = sp.sqrt(5) - sp.sqrt(2)
y = sp.sqrt(3) + sp.sqrt(2)

# Rationalize the expression for x
x_rationalized = (x * (sp.sqrt(3) - sp.sqrt(2))) / ((sp.sqrt(3) + sp.sqrt(2)) * (sp.sqrt(3) - sp.sqrt(2)))
print(x_rationalized)

Simplifying the expression, we get:

x = (√5 - √2)(√3 - √2) / (√3)^2 - (√2)^2

x = (√5 - √2)(√3 - √2) / 3 - 2

x = (√5 - √2)(√3 - √2) / 1

x = (√5 - √2)(√3 - √2)

Rationalizing the Expression for y

We have y = (√3 + √2) / (√3 - √2). To rationalize this expression, we multiply both the numerator and denominator by the conjugate of the denominator, which is (√3 + √2).

# Rationalize the expression for y
y_rationalized = (y * (sp.sqrt(3) + sp.sqrt(2))) / ((sp.sqrt(3) - sp.sqrt(2)) * (sp.sqrt(3) + sp.sqrt(2)))
print(y_rationalized)

Simplifying the expression, we get:

y = (√3 + √2)(√3 + √2) / (√3)^2 - (√2)^2

y = (√3 + √2)(√3 + √2) / 3 - 2

y = (√3 + √2)(√3 + √2) / 1

y = (√3 + √2)(√3 + √2)

Finding the Values of the Given Expressions

Now that we have rationalized the expressions for x and y, we can use these rationalized expressions to find the values of the given expressions.

Finding the Value of x² - y²

We have x² - y² = ((√5 - √2)(√3 - √2))^2 - ((√3 + √2)(√3 + √2))^2

Expanding and simplifying the expression, we get:

x² - y² = (√5 - √2)^2(√3 - √2)^2 - (√3 + √2)^2(√3 + √2)^2

Q: What is rationalizing an expression?

A: Rationalizing an expression means removing any radicals from the denominator of a fraction. This is done by multiplying both the numerator and denominator by the conjugate of the denominator.

Q: How do you rationalize an expression?

A: To rationalize an expression, you need to follow these steps:

Identify the radical in the denominator.
Multiply both the numerator and denominator by the conjugate of the denominator.
Simplify the expression.

Q: What is the conjugate of a denominator?

A: The conjugate of a denominator is the expression obtained by changing the sign of the radical in the denominator. For example, if the denominator is √3 + √2, the conjugate is √3 - √2.

Q: How do you find the value of x² - y²?

A: To find the value of x² - y², you need to substitute the rationalized expressions for x and y into the equation. Then, simplify the expression using the rules of algebra.

Q: How do you find the value of x² + 2xy + y²?

A: To find the value of x² + 2xy + y², you need to substitute the rationalized expressions for x and y into the equation. Then, simplify the expression using the rules of algebra.

Q: How do you find the value of x² + xy + y²?

A: To find the value of x² + xy + y², you need to substitute the rationalized expressions for x and y into the equation. Then, simplify the expression using the rules of algebra.

Q: How do you find the value of x² + y²?

A: To find the value of x² + y², you need to substitute the rationalized expressions for x and y into the equation. Then, simplify the expression using the rules of algebra.

Q: What are some common mistakes to avoid when rationalizing expressions?

A: Some common mistakes to avoid when rationalizing expressions include:

Not multiplying both the numerator and denominator by the conjugate of the denominator.
Not simplifying the expression after rationalizing.
Not checking for any remaining radicals in the denominator.

Q: How can I practice rationalizing expressions?

A: You can practice rationalizing expressions by working through examples and exercises in your textbook or online resources. You can also try creating your own examples and challenging yourself to rationalize them.

Q: What are some real-world applications of rationalizing expressions?

A: Rationalizing expressions has many real-world applications, including:

Simplifying complex fractions in finance and economics.
Solving equations in physics and engineering.
Working with probability and statistics.

By following these steps and practicing rationalizing expressions, you can become more confident and proficient in solving problems involving rational expressions.