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What is the first step in the solution of 3x2+6x=12 by completing the square?
A: r3+r=2
B: r2+2r=4
C: 3r2+6r+9=12+9
D: 3r2+6r+36=12+36

Respuesta :

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Answer:

B: r² + 2r = 4

Explanation:

[tex]\rightarrow \sf 3x^2+6x=12[/tex]

divide both sides by 3

[tex]\rightarrow \sf x^2+2x=4[/tex]    ← This is the result of the first step.

factor out the common term

[tex]\rightarrow \sf x(x+2) = 4[/tex]

set to 0

[tex]\rightarrow \sf x = 4, \ x+2 = 4[/tex]

simplify

[tex]\rightarrow \sf x = 4, \ x= 2[/tex]
  • 3x²+6x=12

Divide all terms by a i.e 3

We get

  • x²+2x=4

Or

  • r²+2r=4

Option B is correct

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