If a = 5 + 2โˆš6 and b = 1/a, then what will be the value of a^2+b^2 ?

If a = 5 + 2โˆš6 and b = 1/a, then what will be the value of a^2+b^2 ? - Part 2
If a = 5 + 2โˆš6 and b = 1/a, then what will be the value of a^2+b^2 ? - Part 3

Remove Ads
Teachoo ยท Class 9 Explore Class 9

Transcript

If a = 5 + 2โˆš6 and b = 1/๐‘Ž, then what will be the value of ๐‘Ž^2+๐‘^2 ? a = 5 + 2โˆš6 b = 1/๐‘Ž = 1/(5 + 2โˆš6) = 1/(5 + 2โˆš6) ร— (5 โˆ’ 2โˆš6)/(5 โˆ’ 2โˆš6) = (5 โˆ’ 2โˆš6)/(5^2 โˆ’ (2โˆš6)^2 ) = (5 โˆ’ 2โˆš6)/(25 โˆ’ 24) We know that ใ€–(๐‘Ž+๐‘)ใ€—^2 = ๐‘Ž^2+๐‘^2+ 2๐‘Ž๐‘ ๐’‚^๐Ÿ+๐’ƒ^๐Ÿ = ใ€–(๐’‚+๐’ƒ)ใ€—^๐Ÿ โˆ’ ๐Ÿ๐’‚๐’ƒ Here, ๐’‚+๐’ƒ = (5+2โˆš6)+5(5โˆ’2โˆš6) ๐’‚๐’ƒ = (5+2โˆš6) (5โˆ’2โˆš6) Thus, ๐‘Ž^2+๐‘^2 = ใ€–(๐‘Ž+๐‘)ใ€—^2 โˆ’ 2๐‘Ž๐‘ ๐‘Ž^2+๐‘^2=ใ€–10ใ€—^2โˆ’2 ร— 1 =100โˆ’2 =๐Ÿ—๐Ÿ–

Davneet Singh's photo - Co-founder, Teachoo

Made by

Davneet Singh

Davneet Singh is an IIT Kanpur graduate and has been teaching for 16+ years. At Teachoo, he breaks down Maths, Science and Computer Science into simple steps so students understand concepts deeply and score with confidence.

Many students prefer Teachoo Black for a smooth, ad-free learning experience.