2x²-xy-3y²
=2x²+2xy-3xy-3y²
=2(x²+xy)-3(xy+y²) 已知x²+xy=3,xy+y²=-2,
=2×3-3×(-2)
=6+6
=12
已知x2;+xy=3,xy+y=-2,求代数式2x2;-xy-3y2;的值
已知x2;+xy=3,xy+y=-2,求代数式2x2;-xy-3y2;的值
已知x²+xy=3,xy+y²=-2,求代数式2x²-xy-3y²
已知x²+xy=3,xy+y²=-2,求代数式2x²-xy-3y²
数学人气:659 ℃时间:2019-10-17 01:35:54
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