2【a-1】²-12【a-1】+18 【x²-2xy+y²】+【-2x+2y】+1a²-8ab+16b²x+y=0.2,x+3y=1 求3x²+12xy+12y²的值1.2【a-1】²-12【a-1】+18 2.【x²-2xy+y²】+【-2x+2y】+13.a²-8ab+16b²4.x+y=0.x+3

2【a-1】²-12【a-1】+18 【x²-2xy+y²】+【-2x+2y】+1a²-8ab+16b²x+y=0.2,x+3y=1 求3x²+12xy+12y²的值1.2【a-1】²-12【a-1】+18 2.【x²-2xy+y²】+【-2x+2y】+13.a²-8ab+16b²4.x+y=0.x+3
2【a-1】²-12【a-1】+18 【x²-2xy+y²】+【-2x+2y】+1
a²-8ab+16b²
x+y=0.2,x+3y=1 求3x²+12xy+12y²的值
1.2【a-1】²-12【a-1】+18
2.【x²-2xy+y²】+【-2x+2y】+1
3.a²-8ab+16b²
4.x+y=0.x+3y=1 求3x²+12xy+12y²的值

2【a-1】²-12【a-1】+18 【x²-2xy+y²】+【-2x+2y】+1a²-8ab+16b²x+y=0.2,x+3y=1 求3x²+12xy+12y²的值1.2【a-1】²-12【a-1】+18 2.【x²-2xy+y²】+【-2x+2y】+13.a²-8ab+16b²4.x+y=0.x+3
2【a-1】²-12【a-1】+18
=2【（a-1）²-6（a-1）＋9】
=2（a-1-3）²
=2（a-4）²
【x²-2xy+y²】+【-2x+2y】+1
=（x-y）²-2（x-y）＋1
=（x-y-1）²
a²-8ab+16b²
=(a-4b)²
x+y=0.2,x+3y=1
相加,得
2x＋4y=1.2
x＋2y=0.6
所以
3x²+12xy+12y²
=3(x²＋4xy＋4y²)
=3(x+2y)²
=3×0.6²
=1.08

2【a-1】²-12【a-1】+18
=2｛【a-1】²-6【a-1】+9｝
=2(a-1-3)²
=2(a-4)²
【x²-2xy+y²】+【-2x+2y】+1
=(x-y)²-2(x-y)²+1
=(x-y-1)²
a²-8ab+16b&...

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2【a-1】²-12【a-1】+18
=2｛【a-1】²-6【a-1】+9｝
=2(a-1-3)²
=2(a-4)²
【x²-2xy+y²】+【-2x+2y】+1
=(x-y)²-2(x-y)²+1
=(x-y-1)²
a²-8ab+16b²
= a²-2a(4b)+(4b)²
=(a-4b)²
x+y=0.2，x+3y=1 求3x²+12xy+12y²的值
3X²+12XY+12Y²
=3(X²+4XY+4Y²)
=3(X+2Y)²
由已知 x+y=0.2 x+3y=1
两式相加后除以2，得x+2y=0.6
所以原式=3*0.6²=1.08

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