(4) 答案正确的是C
3 （1） x² － 36 = 0
x² = 36
x = ±√36 ＝±6
所以 x1 = -6 x2 = 6
(2) 3x² - 1/3 = 0
3x² = 1/3
x² = 1/9
x = ±√（1/9) = ±1/3
所以, x1 = - 1/3 , x2 = 1/3
(3) 2t² - 98 = 0
2t² = 98
t² = 49
t = ±√49 ＝±7
所以 t1 = - 7 , t2 = 7
(4) 16x² - 49 = 0
x² = 49/16
x = ±√（49/16) =±7/4
所以, x1 = -7/4 x2 = 7/4