Toán Lớp 8: Tính a)( 2x -1)² b) ( 3 + 2y)² c) (3x -1 )²

Question

Toán Lớp 8:  Tính  a)( 2x -1)²                                                 b) ( 3 +  2y)²                                   c) (3x -1 )²            d) x ³ + 8                                     e) 8x ³ – 27                                      f) ( 2x – 3y) ³

minhtuyethue · Answer

Giải đáp+ giải th&iacute;ch c&aacute;c bước giải        a)( 2x -1)&sup2;=(2x)&sup2;-2.2x.1+1&sup2;                        =4x&sup2;-4x+1       b)(3+2y)&sup2; =3&sup2;+2.3.2y-(2y)&sup2;                         =9+12y-4y&sup2;       c)(3x-1)&sup2;=(3x)&sup2;-2.3x.1+1&sup2;                      =9x&sup2;-6x+1       d) x&sup3;+8= x&sup3;+2&sup3;                    =(x+2)(x&sup2;-2x+4)       e) 8x&sup3;-27=(2x)&sup3;-3&sup3;                       =(2x-3)(4x&sup2;+6x+9)        f)(2x-3y)&sup3;=(2x)&sup3;-3.(2x)&sup2;.3y+3.2x.(3y)&sup2;-(3y)&sup3;                         =8x&sup3;-36x&sup2;y+54xy&sup2;-27y&sup3;         Ch&uacute;c bạn học tốt^^

haiyemy · Answer

$a) (2x-1)^{2}$ = $4x^2 - 4x +1^{}$ (HĐT số 2)   $b) (3+2y)^{2}$ = $9 + 12y +4y^{2}$ (HĐT số 1)   $c) (3x-1)^{2}$ = $9x^2 - 6x +1^{}$ (HĐT số 2)   $d) x^3+8^{}$ = $(x+2)(x^2-2x+4)^{}$ (HĐT số 6)   $e) 8x^3-27^{}$ = $(2x-3)(4x^2+6x+9)^{}$ (HĐT số 7)   $d) (2x-4y)^{3}$ = $8x^3-12x^2y+54xy^2-27y^{3}$ (HĐT số 5)