Q: a, b, c, d are real numbers such that
a +b +c +d =5
a^2 +b^2 +c^2 +d^2 =15
The maximum a=?? 問:a,b,c,d是實數,使得
a + b + c + d = 5
a ^ 2 + b ^ 2 + c ^ 2 + d ^ 2 = 15
最大a 值 = ??