(1)设x²+y²+2=3,求-3x²-3y²的值(2)若x-y=5,-xy=3,求(7x+4y+xy)-6(5/6y+x-xy)的值.

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(1)设x²+y²+2=3,求-3x²-3y²的值(2)若x-y=5,-xy=3,求(7x+4y+xy)-6(5/6y+x-xy)的值.(1)设x²+

(1)设x²+y²+2=3,求-3x²-3y²的值(2)若x-y=5,-xy=3,求(7x+4y+xy)-6(5/6y+x-xy)的值.
(1)设x²+y²+2=3,求-3x²-3y²的值
(2)若x-y=5,-xy=3,求(7x+4y+xy)-6(5/6y+x-xy)的值.

(1)设x²+y²+2=3,求-3x²-3y²的值(2)若x-y=5,-xy=3,求(7x+4y+xy)-6(5/6y+x-xy)的值.
1、
x²+y²=1
两边乘-3
-3x²-3y²=-3
2、
-xy=3
xy=-3
原式=7x+4y+xy-5y-6x+6xy
=x-y+7xy
=5+7×(-3)
=-16

(1)设x²+y²+2=3,求-3x²-3y²的值
x²+y²+2=3
x²+y²=1
-3x²-3y²=-3(x²+y²)=-3*1=-3

(2)若x-y=5,-xy=3, 求(7x+4y+xy)-6(5/6y+x-xy)...

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(1)设x²+y²+2=3,求-3x²-3y²的值
x²+y²+2=3
x²+y²=1
-3x²-3y²=-3(x²+y²)=-3*1=-3

(2)若x-y=5,-xy=3, 求(7x+4y+xy)-6(5/6y+x-xy)的值
(7x+4y+xy)-6(5/6y+x-xy)
=7x+4y+xy-5y-6x+6xy
=x-y+7xy
=5+7*(-3)
=5-21
=-16

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(1)因为x²+y²+2=3,即x²+y²=1,-3x²-3y²=-3(x²+y²)=-3
(2)(7x+4y+xy)-6(5/6y+x-xy)化简得x-y+7xy=5-7*3=-16