If you would like to find the values of j and k, you can do this using the following steps:
8x^3 - 125 = (2x - 5) * (jx^2 + kx + 25)
8x^3 - 125 = 2jx^3 + 2kx^2 + 50x - 5jx^2 - 5kx - 125
8x^3 = 2jx^3
4x^3 = jx^3
j = 4
2kx^2 + 50x - 5jx^2 - 5kx = 0
2kx^2 + 50x - 20x^2 - 5kx = 0
2kx^2 - 20x^2 + 50x - 5kx = 0
2kx - 20x + 50 - 5k = 0
2x(k - 10) = 5k - 50
2x(k - 10) = 5(k - 10)
k = 10
The correct result would be: j = 4 and k = 10.