Let be real numbers such that they satisfy the system of equations above.
The maximum value of can be expressed as , where and are coprime positive integers. Find the value of .
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The first thing we can do is to express b and c in terms of a .
b 2 + c 2 = 2 0 1 4 − a 2 ( 1 )
2 b + 3 c = 8 6 − a ( 2 )
Then applying the Cauchy- Schwarz Inequality (As in the tag), We will have:
( 2 2 + 3 2 ) ( b 2 + c 2 ) ≥ ( 2 b + 3 c ) 2
Substituting ( 1 ) and ( 2 ) ,
( 1 3 ) ( 2 0 1 4 − a 2 ) ≥ ( 8 6 − a ) 2
Expanding and Manipulating, we will get:
0 ≥ 7 a 2 − 8 6 a − 9 3 9 3
Which gives the range of possible values for a which is:
− 3 1 ≤ a ≤ 7 3 0 3
The maximum value of a is 7 3 0 3 and gives m = 3 0 3 , n = 7 and the required answer which is m + n = 3 1 0