51.已知x>0, 且。試求x2 + =79。試求x+ 之值為何? (A)6 (B)8 (C)9 (D)16
(x+)2
=x2+2.x.+
=79+2
=81
(x+)2=81所以(x+ )=9
51.已知x>0, 且。試求x2 +=79。試求x+ 之值為何? (A)6..-阿摩線上測驗