Toán Lớp 8: phân tích đa thức thành nhân tử:
a)(3x-y)^2-49
b)5x^2-5xy-10x+10y
c)x^2-9x-22
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Toán Lớp 8: phân tích đa thức thành nhân tử:
a)(3x-y)^2-49
b)5x^2-5xy-10x+10y
c)x^2-9x-22
Comments ( 2 )
a) (3x-y)² – 49
= (3x-y)² – 7²
= (3x-y – 7)(3x-y + 7)
b) 5x² – 5xy – 10x + 10y
= 5x(x-y) – 10(x-y)
= (x-y)(5x-10)
= (x-y)[5(x-2)]
= 5(x-y)(x-2)
c) x² – 9x – 22
= x² + 2x – 11x – 22
= x(x+2) – 11(x+2)
= (x+2)(x-11)