- #1
PlasmaSphere
- 82
- 1
1. A cubic polynomial is given by (f)x = x3 + x2 - 10x + 8
1) i) Show that (x -1) is a factor of f(x)
ii) Factorise f(x) fully
iii) Sketch the graph
2. Factor theorem?
3. Attempt at solution
i) I know that f(1) = 0, so (x - 1) is a factor of (f)x = x3 + x2 - 10x + 8
ii) I think i am correct in saying that since you know (x - 1) is a factor you can write it like this; ( x-1 )( x2 - 10x + 8 ), i just don't know where to go from there. I don't think you can factorise x2 - 10x + 8 any further?
I presume that by factorising fully, they mean in the form (x-a)(x-b)(x-c), i just can't seem to get there.
1) i) Show that (x -1) is a factor of f(x)
ii) Factorise f(x) fully
iii) Sketch the graph
2. Factor theorem?
3. Attempt at solution
i) I know that f(1) = 0, so (x - 1) is a factor of (f)x = x3 + x2 - 10x + 8
ii) I think i am correct in saying that since you know (x - 1) is a factor you can write it like this; ( x-1 )( x2 - 10x + 8 ), i just don't know where to go from there. I don't think you can factorise x2 - 10x + 8 any further?
I presume that by factorising fully, they mean in the form (x-a)(x-b)(x-c), i just can't seem to get there.