You are Here: Home >< Maths

# Would I get marks for this solution? watch

1. ___
2. (Original post by Dooderman)
The question is as follows:
Find the values of c and d so that 2x^3 + 5x^2 + cx + d is exactly divisible by (x - 2)(x + 3).

Worked solution:
(x - 2)(x + 3) = x^2 + 3x - 2x - 6 = x^2 + x - 6
2x (x^2 + x - 6) = 2x^3 + 2x^2 - 12x
3 (x^2 + x - 6) = 3x^2 + 3x - 18
2x^3 + 5x^2 - 9x - 18

Hence, c = -9, d = -18.

This is the correct answer, however the book uses a different method to find the answer.

Textbook solution:
f(2) = ....
f(-3) = ...
Combination of f(2) and f(-3).
Hence, gives c = -9, d = -18.
You should get the marks. (but your way relies on quite a bit of guessing and trial-and-error, I'd suggest learning the intended method; it's a lot more systematic)

### Related university courses

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: July 17, 2017
Today on TSR

### Edexcel GCSE Maths Unofficial Markscheme

Find out how you've done here

Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams