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)+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