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Solve the equation by completing the square. Round to the nearest hundredth if necessary.

x^2 + 3x = 25

1 Answer

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Simplifying x2 + 3x = 25
Reorder the terms: 3x + x2 = 25
Solving 3x + x2 = 25 Solving for variable 'x'.
Reorder the terms: -25 + 3x + x2 = 25 + -25
Combine like terms: 25 + -25 = 0 -25 + 3x + x2 = 0
Begin completing the square. Move the constant term to the right: Add '25' to each side of the equation. -25 + 3x + 25 + x2 = 0 + 25
Reorder the terms: -25 + 25 + 3x + x2 = 0 + 25
Combine like terms: -25 + 25 = 0 0 + 3x + x2 = 0 + 25 3x + x2 = 0 + 25 Combine like terms: 0 + 25 = 25 3x + x2 = 25 The x term is 3x.
Take half its coefficient (1.5). Square it (2.25) and add it to both sides.
Add '2.25' to each side of the equation. 3x + 2.25 + x2 = 25 + 2.25
Reorder the terms: 2.25 + 3x + x2 = 25 + 2.25
Combine like terms: 25 + 2.25 = 27.25 2.25 + 3x + x2 = 27.25
Factor a perfect square on the left side: (x + 1.5)(x + 1.5) = 27.25
Calculate the square root of the right side: 5.220153254
Break this problem into two subproblems by setting (x + 1.5) equal to 5.220153254 and -5.220153254.
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