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 ? You are here
Example 18
Example 19 Important
Rationalising
Last updated at April 16, 2024 by Teachoo
If a = 5 + 2√6 and b = 1/𝑎, then what will be the value of 𝑎^2+𝑏^2 ? a = 5 + 2√6 b = 1/𝑎 = 1/(5 + 2√6) = 1/(5 + 2√6) × (5 − 2√6)/(5 − 2√6) = (5 − 2√6)/(5^2 − (2√6)^2 ) = (5 − 2√6)/(25 − 24) We know that 〖(𝑎+𝑏)〗^2 = 𝑎^2+𝑏^2+ 2𝑎𝑏 𝒂^𝟐+𝒃^𝟐 = 〖(𝒂+𝒃)〗^𝟐 − 𝟐𝒂𝒃 Here, 𝒂+𝒃 = (5+2√6)+5(5−2√6) 𝒂𝒃 = (5+2√6) (5−2√6) Thus, 𝑎^2+𝑏^2 = 〖(𝑎+𝑏)〗^2 − 2𝑎𝑏 𝑎^2+𝑏^2=〖10〗^2−2 × 1 =100−2 =𝟗𝟖