tentukan akar persamaan brikut 1. X^2+2x-15=0 2.X^2-4=0 3.4x^2+5x-21

1. x²+2x-15 = 0
(x+5)(x-3) = 0
x = -5 atau x = 3
2. x²-4 = 0
(x+2)(x-2) = 0
x = -2 atau x = 2
3. 4x²+5x-21 = 0
(4x-7)(x+3) = 0
4x = 7 | x = -3
x = 7/4 atau x = -3