Explanation:
0.2x² − 0.8x = 1.6
Multiply both sides by 5.
x² − 4x = 8
Complete the square by adding 4 to both sides.
x² − 4x + 4 = 12
(x − 2)² = 12
x − 2 = ±√12
x = 2 ± √12
The positive solution is x = 2 + √12 ≈ 5.46.
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