Bài 1.a.2x(3x + 2) - 3x(2x + 3)= 2x.3x + 2x.2 - 3x.2x - 3x.3= 6x2 + 4x - 6x2 - 9x= -5xb.(x + 2)3 + (x - 3)3 - x2(x + 5)= (x3 + 6x2 + 12x + 8) + (x2 - 6x + 9) - (x3 + 5x2)= x3 + 6x2 + 12x + 8 + x2 - 6x + 9 - x3 - 5x2= (x3 - x3) + (6x2 + x2 - 5x2) + (12x - 6x) + 9= 2x2 + 6x + 9c.

A.2X(3X + 2) - 3X(2X + 3)= 2X.3X + 2X.2 - 3X.2X - 3X.3= 6X2 + 4X...

Lớp 8 Toán Đề thi giữa học kì 1 Toán lớp 8 năm 2021 - 2022 có đáp án (4 đề)

Bài 1.a.2x(3x + 2) - 3x(2x + 3)= 2x.3x + 2x.2 - 3x.2x - 3x.3= 6x

+ 4x - 6x

- 9x= -5xb.(x + 2)

+ (x - 3)

- x

(x + 5)= (x

+ 6x

+ 12x + 8) + (x

- 6x + 9) - (x

+ 5x

)= x

+ 6x

+ 12x + 8 + x

- 6x + 9 - x

- 5x

= (x

- x

) + (6x

+ x

- 5x

) + (12x - 6x) + 9= 2x

+ 6x + 9c.