I'm working on a math problem but I am having a hard time figuring out the method used by my textbook to make this factorization:

$$x^4 + 10x^3 + 39x^2 + 70x + 50 = (x^2 + 4x + 5)(x^2 + 6x + 10)$$

I've tried to see if this equation can be factored by grouping or by long division to no avail. Any help would be greatly appreciated.