-(x2+y2)+[-3xy-(x2-y2)]化简X=-1,y=2X2表示X的2次方 3XY表示XY乘3

问题描述:

-(x2+y2)+[-3xy-(x2-y2)]化简X=-1,y=2
X2表示X的2次方 3XY表示XY乘3

=-(-2+4)+(7-2)
=-2+5
=3

-(x2+y2)+[-3xy-(x2-y2)]
=-x²-y²-3xy-x²+y²
=-2x²-3xy
=-x(2x+3y)
=-(-1)[(-1×2)+3×2)]
=-2+6
=4