2. x2 – y2 + 10x – 6y +16 = x2 + 10x + 25 – y2 – 6y – 9= (x2 + 10x + 25) – (y2 + 6y + 9)= (x + 5)2 – (y + 3)2= (x + 5 + y + 3)(x + 5 – y – 3)= (x + y + 8)(x – y + 2)

(4 ĐIỂM) PHÂN TÍCH ĐA THỨC THÀNH NHÂN TỬ

Lớp 8 Toán DE THI 8

2. x

– y

+ 10x – 6y +16 = x

+ 10x + 25 – y

– 6y – 9= (x

+ 10x + 25) – (y

+ 6y + 9)= (x + 5)

– (y + 3)

= (x + 5 + y + 3)(x + 5 – y – 3)= (x + y + 8)(x – y + 2)