Question

公式法12a^2-4a-9a^3, (x+y)^2-10(x+y)+25, (x^2+y^2)^2-4x^2y^2. (x+y)^2-2(x^2-y^2)+(x-y)^2

十字相乘法x^2+六分之五+六分之一 x^5-10x^4+16x^3, x^2y^2+20x^2y^2+64xy^2
请在中午十二点前回答

Answer 1

12a^2-4a-9a^3
=-a(9a^2-12a+4)
=-a(3a-2)^2

(x+y)^2-10(x+y)+25
=(x+y-5)^2

(x^2+y^2)^2-4x^2y^2.
=(x^2+y^2-2xy)(x^2+y^2+2xy)
=(x-y)^2(x+y)^2

(x+y)^2-2(x^2-y^2)+(x-y)^2
=(x+y-x+y)^2
=4y^2

十字相乘法x^2+六分之五+六分之一 (题目有误吧)
=x^2+1

x^5-10x^4+16x^3
=x^3(x^2-10x+16)
=x^3()(x-2)(x-8)

x^2y^2+20x^2y^2+64xy^2 题目有误
=21x^2y^2+64xy^2
=xy^2(21x+64)

追问

是加六分之五X

追答

十字相乘法x^2+六分之五+六分之一
=(6x^2+5x+1)/6
=(2x+1)(3x+1)/6

Answer 2

1、12a^2-4a-9a^3=-a（9a²-12a+4）=-a（3a-2）²
2、 (x+y）²-10(x+y)+25=[（x+y）-5]²=（x+y-5）²
3、 (x²+y²)²-4x²y²=(x²)²+2x²y²+(y²)²-4x²y²
=(x²)²-2x²y²+(y²)²
=(x²-y²)²=[(x+y)(x-y)]²=（x+y）²（x-y)²
4、(x+y)²-2(x²-y²)+(x-y)²
=(x+y)²-2（x+y)(x-y)+(x-y)²

=[（x+y）-（x-y）]²
=（2y）²
=4y²
5、x^5-10x^4+16x^3
=x^3(x^2-10x+16)=x^3(x-2)(x-8)
6、x^2y^2+20x^2y^2+64xy^2
题目不对

追问

打错了，是x^3y^2+20x^2y^2+64xy^2

Answer 3

你说的是什么意思？有点不懂

追问

帮忙求一下