已知x²+xy=3,y²+xy=-2,求下列代数式的值.(1)x²+4xy+3y² (2)x²-y²
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已知x²+xy=3,y²+xy=-2,求下列代数式的值.(1)x²+4xy+3y² (2)x²-y²
已知x²+xy=3,y²+xy=-2,求下列代数式的值.
(1)x²+4xy+3y² (2)x²-y²
已知x²+xy=3,y²+xy=-2,求下列代数式的值.(1)x²+4xy+3y² (2)x²-y²
(1)x²+4xy+3y²
=x²+xy +3y²+3xy
=(x²+xy)+3(y²+xy)
=3-6
=-3
(2)x²-y²
=x²+xy-y²-xy
=(x²+xy)-(y²+xy)
=3-(-2)
=5