不解方程2x+y=5;x-3y=1,求7y(x-3y)²-2(3y-x)³的值.

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不解方程2x+y=5;x-3y=1,求7y(x-3y)²-2(3y-x)³的值.

不解方程2x+y=5;x-3y=1,求7y(x-3y)²-2(3y-x)³的值.
不解方程2x+y=5;x-3y=1,求7y(x-3y)²-2(3y-x)³的值.

不解方程2x+y=5;x-3y=1,求7y(x-3y)²-2(3y-x)³的值.
7y(x-3y)²-2(3y-x)³
=7y(3y-x)²-2(3y-x)³
=(3y-x)²[7y-2(3y-x)]
=(3y-x)²(7y-6y+2x)
=(3y-x)²(y+2x)
=(1)*(5)
=5

7y+2

7y(x-3y)²-2(3y-x)³
=7y(x-3y)²+2(x-3y)³
=(x-3y)²×(7y+2x-6y)
=1×5
=5

7y(x-3y)²-2(3y-x)³
=7y(x-3y)²+2(x-3y)³
=(x-3y)²[7y+2(x-3y)]
=(x-3y)²[7y+2x-6y)]
=2x+y
=5