You are Here: Home >< Maths

# Find the x coordinates of the curve using calculus watch

1. Answers are 1 and -1 but how?
2. (Original post by Jyashi)

Answers are 1 and -1 but how?
differentiate and set equal to zero
3. (Original post by Jyashi)

Answers are 1 and -1 but how?
y=x + x^-1
dy/dx = 1 - x^-2=0
1=1/x^2
x^2 = 1
x = 1 or -1
4. The tangent being parallel to the x-axis means the gradient is zero.
5. Thanks guys it makes sense now. Ofcourse, why didnt i think that tangent being parallel to x means its either a min or max point and therefore gradient is 0

### 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: March 7, 2016
The home of Results and Clearing

### 3,523

people online now

### 1,567,000

students helped last year
Today on TSR

### IT'S TODAY!

A-level results chat here

### University open days

1. Bournemouth University
Fri, 17 Aug '18
2. University of Bolton
Fri, 17 Aug '18
3. Bishop Grosseteste University
Fri, 17 Aug '18
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

## Groups associated with this forum:

View associated groups

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE