Toán Lớp 8: a) 7x – 7y + $x^{2}$y – x$y^{2}$
b) $x^{2}$ – $y^{2}$ + 6x + 9
c) $x^{2}$ – 8x + 15
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Toán Lớp 8: a) 7x – 7y + $x^{2}$y – x$y^{2}$
b) $x^{2}$ – $y^{2}$ + 6x + 9
c) $x^{2}$ – 8x + 15
Comments ( 2 )
a) =7(x-y)+xy(x-y)
=(x-y)(7+xy)
b) =(x^2+6x+9)-y^2
=(x+3)^2 -y^2
=(x+3-y)(x+3+y)
c)=x^2-3x-5x+15
=x(x-3)-5(x-3)
=(x-3)(x-5)