2x+y=3且x-3y=5,则y(x-3y)^2+2x(3y-x)^2=?

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2x+y=3且x-3y=5,则y(x-3y)^2+2x(3y-x)^2=?
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2x+y=3且x-3y=5,则y(x-3y)^2+2x(3y-x)^2=?
2x+y=3且x-3y=5,则y(x-3y)^2+2x(3y-x)^2=?

2x+y=3且x-3y=5,则y(x-3y)^2+2x(3y-x)^2=?
2x+y=3 x-3y=5
解得
x= 2 y=-1
y(x-3y)^2+2x(3y-x)^2
=-1*(2+3)^2 + 4*(-5)^2
=-25+100
=75

原式=y*25+2x*25=50x+25y=25*3=75

y(x-3y)^2+2x(3y-x)^2
=y乘5^2+2x乘(—5)^2
=(y+2x)乘5^2
=3乘25
=75
x-3y=5 3y-x=-5

2x+y=3且x-3y=5,则y(x-3y)²+2x(3y-x)²=?
y(x-3y)²+2x(3y-x)²=25y+50x=25(y+2x)=25×3=75