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Which equation is true?
9x2 – 25 = (3x – 5)(3x – 5)
9x2 – 25 = (3x – 5)(3x + 5)
9x2 – 25 = –(3x + 5)(3x + 5)
9x2 – 25 = –(3x + 5)(3x – 5)

Respuesta :

caylus
Hello,

Answer B


But this is not an equation!!!!! (only an expression)

Answer : [tex] 9x^2 - 25 = (3x - 5)(3x + 5) [/tex]

(1) [tex] 9x^2 - 25 = (3x - 5)(3x - 5) [/tex]

Use FOIL method to mulitply (3x – 5)(3x – 5)

[tex] (3x - 5)(3x - 5) = 9x^2 - 30x + 25 [/tex]

(2) [tex] 9x^2 - 25 = (3x - 5)(3x + 5) [/tex]

Use FOIL method to mulitply (3x - 5)(3x + 5)

[tex] (3x - 5)(3x - 5) = 9x^2 - 15x + 15x - 25 = 9x^2 - 25 [/tex]

(3) [tex] 9x^2 - 25 = -(3x + 5)(3x + 5) [/tex]

Use FOIL method to mulitply -(3x + 5)(3x + 5)

[tex] -(3x + 5)(3x + 5) = -(9x^2 + 30x + 25) = -9x^2 -30x -25 [/tex]

(4) [tex] 9x^2 - 25 = -(3x + 5)(3x - 5) [/tex]

Use FOIL method to mulitply -(3x + 5)(3x - 5)

[tex] -(3x + 5)(3x - 5) = -(9x^2 - 25) = -9x^2 + 25 [/tex]

So equation 2 is true

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