Determine the real roots of each equation
(5x^2+20)(3x^2-48) = 0
(x^2+1)(2x^2 - x - 13) = 0
If, as I suspect, you mean . In this case ignore the first bracket.
Divide through by 3 and ignore the first brackets:
This is a classic example using the difference of two squares.
With the second one you can also ignore the first bracket as it has no real solutions