We do not leave an irrational number in the denominator.
So, we rationalise the denominator. Let us look at some examples
Rationalising
Add (3√2+7√3) and (√2−5√3)
Divide 5√11 by 3√33
Multiply 2√15 by 7√5
Simplify (√5+√7)^2
Simplify (√4−√13)(√4+√13)
Simplify (9−√3)(9+√3)
Simplify (3√5−5√2)(4√5+3√2)
Rationalise the denominator of 8/√7
Rationalise the denominator of 1/((8 + 5√2))
Simplify (7√3)/(√10 + √3)−(2√5)/(√6 + √5)−(3√2)/(√15 + 3√2)
Multiple Choice Questions - Chapter 1 Class 9 Maths
Example 16
If a and b are rational numbers and (√11 − √7)/(√11 + √7) = a – b√77, find the value of a and b
Example 17
Find the values of a and b if (7 + 3√5)/(3 + √5) – (7 − 3√5)/(3 − √5) = a+√5 b
Ex 1.4, 5 (i)
If x = 1/(2 − √3), find the value of x^3 − 2x^2 − 7x + 5
If a = 5 + 2√6 and b = 1/a, then what will be the value of a^2+b^2 ?
Example 18
Example 19 Important
Rationalising
Last updated at April 16, 2024 by Teachoo
We do not leave an irrational number in the denominator.
So, we rationalise the denominator. Let us look at some examples
Some Identities (√𝑎)^2=𝑎 √(𝑎^2 )=𝑎 √𝑎𝑏=√𝑎 ×√𝑏 √(𝑎/𝑏)=√𝑎/√𝑏 (√𝑎−√𝑏)(√𝑎+√𝑏)=𝑎−𝑏 (𝑎−√𝑏)(𝑎+√𝑏)=𝑎^2−𝑏 (√𝑎+√𝑏)^2=𝑎+𝑏+2√𝑎𝑏 (√𝑎+√𝑏)(√𝑐+√𝑑)=√𝑎𝑐+√𝑎𝑑 + √𝑏𝑐 + √𝑏𝑑