Toán Lớp 8: 1.Rút gọn a) (2x-3)(x-1)-(x-2)^2-(x-1)(x+1) b)(3x-1)(x+2)- 2(x+3)^2-(x-2)(x-3)

Question

Toán Lớp 8:  1.Rút gọn a) (2x-3)(x-1)-(x-2)^2-(x-1)(x+1) b)(3x-1)(x+2)- 2(x+3)^2-(x-2)(x-3)

thaolanphuobg · Answer

#Sad   a)   (2x-3)(x-1)-(x-2)^2-(x-1)(x+1)   = 2x^2-2x-3x+3-x^2+4x-4-x^2+1   = (2x^2-x^2-x^2)+(-2x-3x+4x)+(3-4+1)   = -x   b)   (3x-1)(x+2)-2(x+3)^2-(x-2)(x-3)   = 3x^2+6x-x-2-2(x^2+6x+9)-(x^2-3x-2x+6)   = 3x^2+5x-2-2x^2-12x-18-x^2+3x+2x-6   = (3x^2-2x^2-x^2)+(5x-12x+3x+2x)+(-2-18-6)   = -2x-26

dananhthumai · Answer

Giải đáp:       Lời giải và giải thích chi tiết:    a) (2x-3)(x-1)-(x-2)^2-(x-1)(x+1)     =2x^2-3x-2x+3-(x^2-2.x.2+2^2)-(x^2-1^2)     =2x^2-5x+3-(x^2-4x+4)-(x^2-1)     =2x^2-5x+3-x^2+4x-4-x^2+1     =(2x^2-x^2-x^2)+(-5x+4x)+(3-4+1)     =-x     b)(3x-1)(x+2)- 2(x+3)^2-(x-2)(x-3)     =3x^2+6x-x-2-2(x^2+2.x.3+3^2)-(x^2-2x-3x+6)     =3x^2+5x-2-2(x^2+6x+9)-(x^2-5x+6)     =3x^2+5x-2-2x^2-12x-18-x^2+5x-6     =(3x^2-2x^2+x^2)+(5x-12x+5x)+(-2-18-6)     =-2x-26