Toán Lớp 8: 1,Rút gọn biểu thức a,(2x+3y+4)^2+(3y+4)^2-2.(2x+3y+4).(3y+4) b,(a+b+c)^2+(a+b-c)^2+(2a-b)^2 c,(5x+y-3).(5x-y-3)-(5x-3)^2 d,(x^2-2x+2).

Question

Toán Lớp 8:  1,Rút gọn biểu thức a,(2x+3y+4)^2+(3y+4)^2-2.(2x+3y+4).(3y+4) b,(a+b+c)^2+(a+b-c)^2+(2a-b)^2 c,(5x+y-3).(5x-y-3)-(5x-3)^2 d,(x^2-2x+2).(x^2-2).(X^2+2x+2).(x^2+2) giúp mình với ạ

tuenhioanh · Answer

Giải đáp:   a)4x&sup2; b)6a&sup2;+3b&sup2;+2c&sup2; c)-y&sup2; d)x^8-16   Lời giải và giải thích chi tiết:   a)(2x+3y+4)&sup2;+(3y+4)&sup2;-2.(2x+3y+4).(3y+4)   =(2x+3y+4)&sup2;-2.(2x+3y+4).(3y+4)+(3y+4)&sup2;   =[(2x+3y+4)-(3y+4)]&sup2;   =(2x+3y+4-3y-4)&sup2;   =(2x)&sup2;   =4x&sup2;   b)(a+b+c)&sup2;+(a+b-c)&sup2;+(2a-b)&sup2;   =[(a+b)+c]&sup2;+[(a+b)-c]&sup2;+4a&sup2;-4ab+b&sup2;   =(a+b)&sup2;+2c(a+b)+c&sup2;+(a+b)&sup2;-2c(a+b)+c&sup2;+4a&sup2;-4ab+b&sup2;   =a&sup2;+2ab+b&sup2;+2ac+2bc+c&sup2;+a&sup2;+2ab+b&sup2;-2ac-2bc+c&sup2;+4a&sup2;-4ab+b&sup2;   =(a&sup2;+a&sup2;+4a&sup2;)+(2ab+2ab-4ab)+(b&sup2;+b&sup2;+b&sup2;)+(2ac-2ac)+(2bc-2bc)+(c&sup2;+c&sup2;)   =6a&sup2;+3b&sup2;+2c&sup2;   c)(5x+y-3)(5x-y-3)-(5x-3)&sup2;   =[(5x-3)+y][(5x-3)-y]-(5x-3)&sup2;   =(5x-3)&sup2;-y&sup2;-(5x-3)&sup2;   =-y&sup2;   d)(x&sup2;-2x+2)(x&sup2;-2)(x&sup2;+2x+2)(x&sup2;+2)   =[(x&sup2;-2)(x&sup2;+2)][(x&sup2;-2x+2)(x&sup2;+2x+2)]   =[(x^2)^2-2^2][(x&sup2;+2)^2-(2x)^2]   =(x^4-4)(x^4+4x&sup2;+4-4x&sup2;)   =(x^4-4)(x^4+4)   =(x^4)^2-4^2   =x^8-16

maingocquynhnhu2k1 · Answer

Giải +giải chi tiết