Zar0ienckeum
Answered

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)

Verified Answer :

caylus

Hello,

Answer B


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

Answer : \(9x^2 - 25 = (3x - 5)(3x + 5)\)

(1) \(9x^2 - 25 = (3x - 5)(3x - 5)\)

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

\((3x - 5)(3x - 5) = 9x^2 - 30x + 25\)

(2) \(9x^2 - 25 = (3x - 5)(3x + 5)\)

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

\((3x - 5)(3x - 5) = 9x^2 - 15x + 15x - 25 = 9x^2 - 25\)

(3) \(9x^2 - 25 = -(3x + 5)(3x + 5)\)

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

\(-(3x + 5)(3x + 5) = -(9x^2 + 30x + 25) = -9x^2 -30x -25\)

(4) \(9x^2 - 25 = -(3x + 5)(3x - 5)\)

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

\(-(3x + 5)(3x - 5) = -(9x^2 - 25) = -9x^2 + 25\)

So equation 2 is true

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