Question

急啊！！数学题 在线等

1. x^2+3xy+2y^2+4x+5y+3
2. x^2-5x+3
3. b^2+c^2+2ab+2ac+2bc
4. (x^2-2x)^2-7(x^2-2x)+12
5. 2x^2-xy-15y^2

麻烦按序号答 再把步骤写出来 谢谢啊！！

Answer 1

1.
x^2+3xy+2y^2+4x+5y+3
=(x+y)(x+2y)+3(x+y)+(x+2y)+3
=(x+y)(x+2y+3)+(x+2y+3)
=(x+y+1)(x+2y+3)

2. x^2-5x+3
=x^2-5x+25/4-25/4+3
=(x-5/2)^2-13/4
=(x-5/2-√13/2)(x-5/2+√13/2)

3.
a^2+b^2+c^2+2ab+2ac+2bc
=(a^2+2ab+b^2)+2c(a+b)+c^2
=(a+b)^2+2c(a+b)+c^2
=(a+b+c)^2

4. (x^2-2x)^2-7(x^2-2x)+12
=(x^2-2x-3)(x^2-2x-4)
=(x^2-2x-3)(x^2-2x+1-5)
=(x^2-2x-3)[(x-1)^2-5]
=(x-3)(x+1)(x-1-√5)(x-1+√5)

5.
2x^2-xy-15y^2
=2x(x-3y)+5y(x-3y)
=(2x+5y)(x-3y)

Answer 2

1.x^2+3xy+2y^2+4x+5y+3
=(x+y)(x+2y)+3(x+y)+(x+2y)+3
=(x+y)(x+2y+3)+(x+2y+3)
=(x+y+1)(x+2y+3)
2.x^2-5x+3=0两根为（5±√13)/2
因此，为（x-5/2+√13/2）（x-5/2-√13/2)
3.
a^2+b^2+c^2+2ab+2ac+2bc
=(a²+2ab+b²)+2c(a+b)+c²
=(a+b)²+2c(a+b)+c²
=(a+b+c)²
4.(x^2-2x)^2-7(x^2-2x)+12
=(x^2-2x-4)(x^2-2x-3)
=(x^2-2x-4)(x-3)(x+1)
5.
2x^2-xy-15y^2
=2x(x-3y)+5y(x-3y)
=(2x+5y)(x-3y)

Answer 3

(x+2y+3)(x+y+1)用降元法 x为0 (2y+3）（y+1) y为0 (x+3)(x+1)

Answer 4

你是要求化简 还是...............

Answer 5

解什么呢？好像没写全吧？
化为规范型或者标准型么？