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Solve the equation by completing the square. Round to the nearest hundredth if necessary. x2 + 2x = 15

User Leebriggs
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2 Answers

4 votes

Answer:

3 AND -5

Explanation:

User Stevenson
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6 votes

x^2+2x=15\\\\x^2+2\cdot x\cdot1=15\ \ \ |+1^2\\\\\underbrace{x^2+2\cdot x\cdot1+1^2}_((a+b)^2=a^2+2ab+b^2)=15+1^2\\\\(x+1)^2=16\to x+1=\pm√(16)\\\\x+1=-4\ \vee\ x+1=4\ \ \ \ |-1\\\\x=-5\ \vee\ x=3
User Jonp
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