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How to solve each equation by completing a square -4x^2+10x-40=-9x^2

2 Answers

3 votes

Answer:x=2,-4

Explanation:

User Ryan Lyu
by
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5 votes

Answer:

x = -4 or 2

Explanation:

-4x² + 10x − 40 = -9x²

First, move the x terms to one side and the constant to the other.

5x² + 10x = 40

Divide by the leading coefficient:

x² + 2x = 8

Take half of the b coefficient, square it, then add to both sides.

(2/2)² = 1

x² + 2x + 1 = 8 + 1

x² + 2x + 1 = 9

Factor the perfect square:

(x + 1)² = 9

Solve for x:

x + 1 = ±3

x = -1 ± 3

x = -4 or 2

User Airen
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