Answer:
-0.1, 1.3
Explanation:
You want the solutions to the quadratic equation 5x² -2x -1 = 4x.
Quadratic
The equation can be put in standard form by subtracting 4x:
5x² -6x -1 = 0
5(x² -6/5x +(6/10)²) -1 -5(6/10)² = 0 . . . . . complete the square
5(x -0.6)² = -2.8 . . . . . . . . . . . . . subtract 2.8
x = 0.6 ± √0.56 = -0.1 or 1.3 . . . . . . . divide by 5 and take square root
Solutions to the equation are x = -0.1 and x = 1.3.
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Additional comment
The square is completed by making the trinomial in parentheses have the form x² -2ax +a², where 'a' is half the coefficient of the x-term. When we add a² inside parentheses, we need to subtract an equivalent quantity outside parentheses.
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