To determine which equation has only one distinct solution, we can look for a quadratic equation that can be factored into a perfect square.
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\( x^2 - 4 = 0 \)
Factors to \( (x-2)(x+2) = 0 \)
Solutions: \( x = 2 \) and \( x = -2 \) (two distinct solutions) -
\( x^2 - 5x + 4 = 0 \)
Factors to \( (x-1)(x-4) = 0 \)
Solutions: \( x = 1 \) and \( x = 4 \) (two distinct solutions) -
\( x^2 + 5x + 4 = 0 \)
Factors to \( (x+4)(x+1) = 0 \)
Solutions: \( x = -4 \) and \( x = -1 \) (two distinct solutions) -
\( x^2 + 4x + 4 = 0 \)
Factors to \( (x+2)(x+2) = 0 \)
Solution: \( x = -2 \) (one distinct solution, repeated)
Thus, the equation that has only one distinct solution is:
\( x^2 + 4x + 4 = 0 \).