If m-n=16andm^2+n^2=400,then find mn
Answers
Answer:
mn = 72
Step-by-step explanation:
Given---> m - n = 16 and m² + n² = 400
To find ----> Value of mn
Solution---> We have an identity as follows
( a - b )² = a² + b² - 2ab
Putting a = m and b = n in it , we get,
=> ( m - n )² = m² + n² - 2 mn
=> ( m - n )² = ( m² + n² ) - 2mn
Putting m - n = 16 and m² + n² = 400 , we get,
=> ( 16 )² = ( 400 ) - 2 mn
=> 256 = 400 - 2mn
=> 2 mn = 400 - 256
=> 2 mn = 144
=> mn = 144 / 2
=> mn = 72
Addotional identities--->
1) ( a + b )² = a² + b² + 2ab
2) (a + b + c )² = a² + b² + c² + 2ab + 2bc + 2ca
3) a² - b² = ( a + b ) ( a - b )
4) a³ + b³ = ( a + b ) ( a² + b² - ab )
5) a³ - b³ = ( a - b ) ( a² + b² + ab )
6) ( a + b )³ = a³ + b³ + 3ab ( a + b )
7) ( a - b )³ = a³ - b³ - 3ab ( a - b )
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