Вычислите x + y дробь 2 √xy если:

a) x = 2√7 - 5, y = 5 + 2√7

б) x = 1 дробь √2 + 1, y = 1 дробь √2 - 1

А) ((2 * (7^1/2) - 5) + (5+2 * (7^1/2)) / 2 * (2 * (7^1/2) - 5) * (2 * (7^1/2) + 5)) ^1/2=

4 * (7^1/2) / 2 * (4*7-25) ^1/2=

2 * (7^1/2) / (28-25) ^1/2 = 2 * (7/3) ^1/2;

б) (((2^1/2-1) + (2^1/2+1)) / (2^1/2+1) (2^1/2-1)):

2 * (1 / (2^1/2+1) (2^1/2-1)) ^1/2=

(2*2^1/2 / (2-1)) / 2 * (1 / (2-1)) ^1/2=

2*2^1/2/2=2^1/2.