初一数学!快啊!答得好30分!决不食言!998^2=123^2-124*122=已知x+y=6且xy=4求(1)x^2+y^2(2)(x-y)^2已知x^2+9y^2-4x+12y+8=0求y^-x值为什么(x-2)^2+(3y+2)^2=0得x=2,y=-2/3

Question

初一数学!快啊!
答得好30分!决不食言!
998^2=
123^2-124*122=
已知x+y=6且xy=4求(1)x^2+y^2 (2)(x-y)^2
已知x^2+9y^2-4x+12y+8=0求y^-x值
为什么(x-2)^2 + (3y+2)^2 = 0
得x = 2, y = -2/3

Answer 1

1.998^2 = (1000-2)^2 = 1000000 - 4000 + 4 = 9960042.123^2 - 124*122 = (124-1)*(122+1) - 124*122= 124*122 - 122 + 124 - 1 - 124*122= 13.(1)x^2+y^2 = (x+y)^2 - 2xy= 36 - 8 = 28(2)(x-y)^2 = (x+y)^2 - 4xy...