# How would you solve this question only using C1 knowledge? Part c btw.Watch

Thread starter 1 year ago
#1
0
quote
1 year ago
#2
(Original post by ImBadAtLife)
It might be easier to see if you factorise, take (x-1) out as a common factor.
1
quote
Thread starter 1 year ago
#3
I already solved it by using Algebraic long division, the answers are 3,1,-1. The issue is that for a C1 question without a calculator it might be a bit hard, also it's worth only 3 marks.
0
quote
1 year ago
#4
it is related to the original function by a simple translation. thus the roots will be translated by the same amount.
2
quote
1 year ago
#5
(Original post by ImBadAtLife)
I already solved it by using Algebraic long division, the answers are 3,1,-1. The issue is that for a C1 question without a calculator it might be a bit hard, also it's worth only 3 marks.
Seems alright for a 3 marker.

If you take out (x-1) you get:
= (x - 1)[(x - 1)^2 - 4]

= (x - 1)[x^2 -2x +1 - 4]

= (x - 1)[x^2 -2x - 3]

= (x - 1)(x - 3)(x + 1)

Giving you x = 1, 3, -1

You don't actually have to go through long division which is general a slower process, I think just taking time to take out a common factor and expand the quadratic would only take a minute with some practice.

Good luck!
0
quote
Thread starter 1 year ago
#6
Ok done took the (x-1), that does make it easier thanks @notnotbatman
1
quote
1 year ago
#7
(Original post by ImBadAtLife)
Ok done took the (x-1), that does make it easier thanks @notnotbatman
if you observe carefully and let the original function =f(x) then the curve they want you to draw is f(x-1) which you should be able to draw from the original graph, the solutions can also be found easily using this way after drawing the graph
0
quote
1 year ago
#8
You shouldn't have to do the actual expansions.
You've been given y = x^3 - 4x which we can call f(x).
y = (x-1)^3 - 4(x-1) can be written as f(x-1) since the 'x' values are replaced by 'x-1'.

From simple graph transformations, you know that f(x - a) translates the graph 'a' units horizontally, so in your question, the original graph is just translated 1 unit to the right. This means you can easily state the roots and the turning point, allowing you to sketch the curve
0
quote
1 year ago
#9
Good grief folks. Listen to the beaÉ¾ .
1
quote
1 year ago
#10
(Original post by Mr M)
Good grief folks. Listen to the beaÉ¾ .
0
quote
X

new posts
Latest
My Feed

### Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

see more

### See more of what you like onThe Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

### University open days

• University of Warwick
Sat, 20 Oct '18
• University of Sheffield
Sat, 20 Oct '18
• Edge Hill University
Faculty of Health and Social Care Undergraduate
Sat, 20 Oct '18

### Poll

Join the discussion

#### Who is most responsible for your success at university

Mostly me (653)
91.07%
Mostly my university including my lecturers/tutors (64)
8.93%