- #1
DeanBH
- 82
- 0
The polynomial f(x) is given by f(x) = x^3 + 4x -5
show x-1 is factor :
f(1)=0
1+4-5=0 Thus it's a factor.
express in form (x-1)(x^2+px+q)
ends up being X^2 + X + 5.
next question is :
hence show the equation f(x) = 0 has one real root state it's value.
i know i have to use b^2 -4ac. If i do that it's -19 which is <0 so it's 1 value. But how do I find the value. And why does all this stuff work.
My teacher is one that just tells you how to do it. I have no idea why I'm doing it and it makes no sense so it's harder to remember. I would get 1or 2 marks out of 3 for this.
Firstly i don't know how to find out what the real number is. and i don't know why this works.
explain plez?! 8D
show x-1 is factor :
f(1)=0
1+4-5=0 Thus it's a factor.
express in form (x-1)(x^2+px+q)
ends up being X^2 + X + 5.
next question is :
hence show the equation f(x) = 0 has one real root state it's value.
i know i have to use b^2 -4ac. If i do that it's -19 which is <0 so it's 1 value. But how do I find the value. And why does all this stuff work.
My teacher is one that just tells you how to do it. I have no idea why I'm doing it and it makes no sense so it's harder to remember. I would get 1or 2 marks out of 3 for this.
Firstly i don't know how to find out what the real number is. and i don't know why this works.
explain plez?! 8D