(x-1)(X-3)=8x^2-4x+3-8=0x^2-4x-5=0(x-5)(x+1)=0x1=5,x2=-1
(x -1)( x-3)+1 =x-4x+3+1 =x-4x+4 =(x-2)
先将原式展开,得 x^2-4x+3-8=0 化简,得 x^2-4x-5=0 十字相乘,得 (x-5)(x+1)=0 x-5=0或x+1=0 解得:x=5或x=-1
(X1)(X3)=8 化简,再因式分解得到 (x+1)(x-5)=0 所以 x=-1或x =5
x-1/x=8/3 同乘以3x得3x^2-3=8x3x^2-8x-3=0(3x+1)(x-3)=0 x=-1/3或x=3
(x-1)(x-3)-8=x^2-4x-5=(x+1)(x-5)
(x+1)(x-1)+2(x+3)=8 x-1+2x+6-8=0 x+2x-3=0(x+3)(x-1)=0 x1=-3; x2=1
(x+1)(x+3)-8=x+4x+3-8=x+4x-5=(x+5)(x-1)有不明白的可以追问!谢谢!!祝学习进步
X^3-8=X^3-2^3=(X-2)(X^2+2X+4)注:就是代公式 a^3-b^3=(a-b)(a^2+ab+b^2)
因为当x=5时原式为0 所以由x-5这一项 (x+1)(x+2)(x+3)-6x7x8=(x-5)(x*x+11x+6)