f'(x)= 4sin2x, f(0) =(-1)

f'(x) = 4 sin 2x, f(0) = (-1)
integralkan f'(x) = 4 sin 2x
maka, f(x) = 4*integral sin x = 4*-1/2*cos 2x = -2 cos 2x + C
masukkan nilai f(0) = (-1) ke persamaan f(x) = -2 cos 2x + C
maka, -1 = -2 cos 2(0) + c
            -1 = -2 cos 0 + c
            -1 = -2*1 + c
            -1 = -2 + c
            c = -1+2 = 1
maka, persamaan f(x) adalah f(x) = -2 cos 2x + 1