初二下学期数学题目,要过程,谢谢啦```

1.-12xy+x^2+36y^2 =-(x^2+36y^2-12xy) =-(x-6y)^2 2.1/4+a^2+a^4 =1/4(4a^4+4a^2+1) =1/4(2a^2+1)^2 3.a^2-8ab+16b^2 =(a-4b)^2 4.(a^2+b^2)^2-4a^2b^2 =(a^2+b^2+2ab)(a^2+b^2+2ab) =(a+b)^2(a-b)^2 5.(1/36a-1/3)a+1 =1/36(a^2-12a+36) =1/36(a-6)^2 6.2(a-1)^2-12(a-1)+18 =2[(a-1)^2-6(a-1)+9] =2(a-1-3)^2 =2(a-4)^2 7.(x^2-2xy+y^2)+(-2x+2y)+1 = (x^2-2xy+y^2)-2(x-y)+1 =(x-y)^2)-2(x-y)+1 =(x-y-1)^2