Bài 2 b/ x2 – xy – 2x + 2y = (x2 – xy) – (2x - 2y) 0,25đ(1,5điểm) =x(x – y) – 2( x – y) = (x – y)(x – 2) 2 2 1 1x x      =2( 1) 12 2 1a/ A= 0,52 2 1 22( 1) 2( 1)=2 2 1 2 ( 1)2 1x x x x     2( 1) 2( 1) 2= d/ B= 2x −x+11 = 2x −x −12+2+1=2(x −x −11)+3

B/ X2 – XY – 2X + 2Y = (X2 – XY) – (2X - 2Y) 0,25Đ(1...

Toán DE THI HKI TOAN 8 CO DAP AN VA MA TRAN

Bài 2 b/ x

– xy – 2x + 2y = (x

– xy) – (2x - 2y) 0,25đ(1,5điểm) =x(x – y) – 2( x – y) = (x – y)(x – 2)

2 1 1x x      =2( 1) 12 2 1a/ A= 0,5

2 1 22( 1) 2( 1)=

2 1 2 ( 1)

1x x x x     2( 1) 2( 1) 2= d/ B= ²_{x −}^x⁺¹₁ = ²^{x −}_{x −1}²⁺²⁺¹⁼²^{(x −}_{x −1}¹⁾⁺³