Question

若x²-8x+13=0.求x²-8x+15分之x四次方-6x三次方-2x²+18x+13的值

Answer 1

解：
(x四次方-6x三次方-2x²+18x+13)÷(x²-8x+15)
=[(x四次方-8x三次方+13x²)+(2x三次方-15x²+18x)-(x²-8x)]÷(x²-8x+13+2)
=[x²(x²-8x+13)+2x(x²-8x+13)]÷(0+2)
=0÷2=0

追问

我那里打错了 最后那里应该是+23的值 再帮忙算算 谢谢。

追答

(x四次方-6x三次方-2x²+18x+23)÷(x²-8x+15)
=[(x四次方-8x三次方+13x²)+(2x三次方-15x²+18x)-(x²-8x)+10]÷(x²-8x+13+2)
=[x²(x²-8x+13)+2x(x²-8x+13)+10]÷(0+2)
=10÷2
=5

Answer 2

(x四次方-6x三次方-2x²+18x+13)/(x²-8x+15)
=[(x四次方-8x三次方+13x²)+2(x三次方-8x²+13x)+(x²-8x-13)]/(x²-8x+13+2)
=[x²(x²-8x+13)+2x(x²-8x+13)+(x²-8x-13)]/(x²-8x+13+2)
=(x²*0+2x*0+0)/(0+2)
=0/2
=0