第一题的八到十题
1个回答
(1).7x²-63=7(x²-9)=7(x+3)(x-3)
(2).a³-a=a(a²-1)=a(a+1)(a-1)
(3).3a²-3b²=3(a²-b²)=3(a+b)(a-b)
(4).y²-9(x+y²)=(y+3x+3y)(y-3x-3y)=(3x+4y)(-3x-2y)= - (3x+4y)(3x+2y)
(5).a(x-y)-b(y-x)+c(x-y)=a(x-y)+b(x-y)+c(x-y)=(x-y)(a+b+c)
(6).x(m+n)-y(n+m)+(m+n)=(m+n)(x-y+1)
(7).(x+y)²-16(x-y)²=(x+y+4x-4y)(x+y-4x+4y)=(5x-3y)(5y-3x)
(8).a²(a-b)²-b²(a-b)²=(a-b)²(a²-b²)=(a-b)²(a+b)(a-b)
(9).(x+y+z)²-(x-y-z)²=(x+y+z+x-y-z)(x+y+z-x+y+z)=(2x)(2y+2z)=4x(y+z)
10,(x+y)²-14(x+y)+49=(x+y-7)²
(1).a²b²-0.01=(ab+0.1)(ab-0.1)
(2).x²y-2xy²+y³=y(x²-2xy+y²)=y(x-y)²
(3).16-(2a+3b)²=(4-2a-3b)(4+2a+3b)
(4).(a²+4)²-16a²=(a²+4+4a)(a²+4-4a)=(a+2)²(a-2)²
(5).x²-xy+y²/4=(x-y/2)²
(6).a²x²+16ax+64=(ax+8)²
