Answer:
{-1, 5} (two real solutions).
Explanation:
On the left side we want x^2, not x?
We need to rewrite x? = 4x - 5 in standard form, that is, as a quadratic with x terms in decreasing powers of x:
x^2 - 4x + 5 = 0
This factors easily to (x - 5)(x + 1) = 0.
We let each factor equal zero (0) separately and solve for x:
{-1, 5} (two real solutions).