已知2x²+12x+18=0,（3y+4)²=（y-4）²,求代数式4x²-12xy+9y²的值

已知2x²+12x+18=0,（3y+4)²=（y-4）²,求代数式4x²-12xy+9y²的值
已知2x²+12x+18=0,（3y+4)²=（y-4）²,求代数式4x²-12xy+9y²的值

已知2x²+12x+18=0,（3y+4)²=（y-4）²,求代数式4x²-12xy+9y²的值
2x²+12x+18=0
x²+6x+9=0
(x+3)²=0
x=-3
(3y+4)²=（y-4）²
(3y+4)²-(y-4)²=0
(3y+4-y+4)(3y+4+y-4)=0
4y(2y+8)=0
8y(y+4)=0
y(y+4)=0
y²+4y=0
4x²-12xy+9y²
=4*(-3)²-12*(-3)y+9y²
=36+36y+9y²
=36+9(y²+4y)
=36+9*0
=36

2x2+12x+18 = 0
(x+3)=0
x = -3
(3y+4)2 =(y-4)2
9y2+24y+16=y2-8y+16
y = 0; y = -4
4x2-12xy+9y2
=(2x-3y)2
= 36