# C2 Differentiation questionWatch

#1
Here is the question:
Given that: Y = x^1.5 + 48x^-1 (x is greater than 0)
A) Find value of x and the value of y when f’(x) = 0
B) Show that the value of y which you found in a is a minimum

It seems simple, I can do the second part but i can't do a because I don't know how to solve f'(x)= 1.5x^0.5 - 48x^-2= 0.

0
7 years ago
#2
Well, use either factorisation or put it into the quadratic formula for a start. Maybe it would look easier if you put the powers as fractions rather than decimals?
0
7 years ago
#3
A)

,...........

x=0, x=4, y=20
1
7 years ago
#4
For part A you need to think about what it means when dy/dx = 0. What does that mean about the curve?
0
7 years ago
#5
This is easy just equate f'x to o and carry out normal fraction substraction. Is x=4?
0
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