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Determine whether the polynomial is a difference of squares and if it is, factor it.


y2 – 225



is a difference of squares: (y – 15)(y + 15)

is not a difference of squares

is a difference of squares: (y + 15)2

is a difference of squares: (y – 15)2

Respuesta :

tonb
Remember these three formulas (really, learn these by heart):

[tex]{(a + b)}^{2} = a^{2} + 2ab + b^{2} [/tex]

[tex]{(a - b)}^{2} = a^{2} - 2ab + b^{2} [/tex]

[tex](a + b)(a - b) = a^{2} - b^{2} [/tex]

The stated formula is a manifestation of the last of these three. So indeed,

[tex](y + 15)(y - 15) = y^{2} - 225[/tex]



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