C1 Help :(

A curve has the equation y=3x-x^3/2

The curve meets the x axis at the origin and at the point A (where y is 0) and has a maximum at the point B

i) find the x coordinate of A

I know I need to make y 0 but I'm having such a hard time factorising it! :frown:

Reply 1

the bear

you can write

x ( 3 - x^? ) = 0

to find ? you have to think about combining the powers of x and x^? to make x^3/2

Reply 2

tigs253

Original post by the bear

you can write

x ( 3 - x^? ) = 0

to find ? you have to think about combining the powers of x and x^? to make x^3/2

Thank you! I now have x(3-x^1/2) but I've never seen x^1/2 or the square root of x in a bracket before so I don't really know how to find x from it

Reply 3

Hanaan999

If it is a root y=0
Therefore x (3-x^1/2)=0
Now if they equal zero either x=0 (the origin) or 3-x^1/2=0
Then x^1/2=3
Since x^1/2 is the same as square root
You know that the square root of x=3
From this you can find x

Posted from TSR Mobile

(edited 7 years ago)

Reply 4

Tyson_Fury

Original post by catrinellis

For part ii u need to differntiate it

Reply 5

tigs253

Original post by Hanaan999

If x^1/2-3=0
Then x^1/2=3
Since x^1/2 is the same as square root
You know that the square root of x=3
From this you can find x

Posted from TSR Mobile

Ahh thank you that makes sense