4 x² - 9 y² = 0
Rewrite this expresion as:
( 2 x )² - ( 3 y )² = 0
So:
4 x² - 9 y² = ( 2 x )² - ( 3 y )² = 0
Apply the difference of two squares formula:
a² - b² = ( a + b ) ( a - b )
In this case:
( 2 x )² - ( 3 y )² = 0
( 2 x + 3 y ) ( 2 x - 3 y ) = 0
Which way is correct? or both?
(4x^2 -9y^2)=0 into xy(4x-9y)=0 or (2x+3y)(2x-3y)=0
3 answers
Correct is:
( 2 x + 3 y ) ( 2 x - 3 y ) = 0
because:
x y ( 4 x - 9 y ) = y ∙ ( 4 x ∙ x - 9 y ∙ x ) = y ∙ ( 4 x² - 9 x y )
That is not your expression:
4 x² - 9 y²
( 2 x + 3 y ) ( 2 x - 3 y ) = 0
because:
x y ( 4 x - 9 y ) = y ∙ ( 4 x ∙ x - 9 y ∙ x ) = y ∙ ( 4 x² - 9 x y )
That is not your expression:
4 x² - 9 y²
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