# Find the equation

• Dec 28th 2012, 06:18 PM
hahalol
Find the equation
Find the equation of the line that passes trough point (0,1) such that the area, S, of the region enclosed by this line and the parabola y=x^2 is (5√5)/6.

This is what I did:
I found the equation of the line which is y=x+1
Then, I put x^2=x+1
x^2-x-1=0
α+β=-1
αβ=-1
S=integral of (x+1-x^2)dx [α,β].
It gave me (5√5)/6.
I don't know how to continue to find out the equation.
• Dec 28th 2012, 06:37 PM
Prove It
Re: Find the equation
How did you manage to get y = x + 1? There are an INFINITE number of lines that this could possibly be. It should be y = mx + 1.
• Dec 28th 2012, 09:38 PM
hahalol
Re: Find the equation
This is what I did:
I found the equation of the line which is y=mx+1
Then, I put x^2=mx+1
x^2-mx-1=0
α+β=m
αβ=-1
S=integral of (mx+1-x^2)dx [α,β].
It gave me 1/6(m+2)^3
I put 1/6(m+2)^3=(5√5)/6
It gave me that m=-2cubic root of 5√5
So, the equation is y=(=-2cubic root of 5√5)x+1

I know that my answer is wrong... because it cannot give a number like this.. but I cannot find out where is my mistake.
• Dec 28th 2012, 10:14 PM
ibdutt
Re: Find the equation
• Dec 29th 2012, 04:44 AM
ibdutt
Re: Find the equation
Attachment 26401Please have the complete solution