Toán 8

M

megamanxza

Bài 1: A=[TEX]x^2+2xy+y^2-4x-4y+1[/TEX]
=[TEX](x+y)^2-4(x+y)+1[/TEX]
Thay x+y=3, ta được:
A=[TEX]3^2-4.3+1[/TEX]=-2.

Bài 2: a/ {x;y}={-4;-3} hoặc {4;3}.
 
L

lamdetien36

Bài 1:
B=x3+y3+3xy=(x+y)(x2−xy+y2)+3xy=x2−xy+y2+3xy=x2+2xy+y2=(x+y)2=12=1B = x^3 + y^3 + 3xy = (x + y)(x^2 - xy + y^2) + 3xy = x^2 - xy + y^2 + 3xy = x^2 + 2xy + y^2 = (x + y)^2 = 1^2 = 1
 
You must log in or register to reply here.
Top Bottom