Having trouble with differential and linear approximation

[Cleowen]

f(x)=x^3/2 with x=4 and deltax=dx=0.1 calculate deltay and dy

I got 0.4 for dy but its wrong, and i can't find deltay. please help! thxs

 

[LCKurtz]

f(x)=x^3/2 with x=4 and deltax=dx=0.1 calculate deltay and dy

I got 0.4 for dy but its wrong, and i can't find deltay. please help! thxs

Show us your work and we will help you fix your mistake.

 

[Millennial]

In your post, do you mean $x\sqrt{x}$ or $\dfrac{x^3}{2}$ by x^3/2?