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2x-y+2z=0 2x-y+2z=16 4x-3y+6z=42 4x-3y+6z=0
(﹣2xy)2=﹣4x2y2 x6÷x3=x2 (x﹣y)2=x2﹣y2 2x+3x=5x
3x+4y-36=0 3x-2y-18=0 2x-2y-24=0 2x-4y-36=0
9x224xy+16y2 9x2+12xy+16y2 9x216y2 9x2+24xy+16y2
-8x6y -6x2y3 -6x6y3 -8x6y3
3x2+2x2=5x 4 (-x2)3=-x 6 (2x2y)2=2x4y2 (x+y2)2=x2+y4
E(Y)=4 E(Y)=3 Var(Y)=24 Var(Y)=25 Var(Y)=23
x2-3y2 x2-6y2 x2-9y2 2x2-6y2
x2+y2-4x+6y-8=0 x2+y2-4x+6y+8=0 x2+y2+4x-6y-8=0 x2+y2+4x-6y+8=0
x4+x4=2x8 x3•x2=x6 (x2y)3=x6y3 (x﹣y)(y﹣x)=x2﹣y2
(x+1)(x+4)=x2+5x+4 (y+4)(y-5)=y2+9y-20 (m+2)(m-3)=m2-m-6 (x-3)(x-6)=x2-9x+18
2x-y+2z=0 2x-y+2z=16 4x-3y+6z=42 4x-3y+6z=0