Thread: Change in y and differentrial dy

1. Change in y and differentrial dy

Let .
Find the change in , when and
Find the differential when and

can i get some help with this please?

thank you

2. Originally Posted by mybrohshi5
Let .
Find the change in , when and
Find the differential when and

can i get some help with this please?

thank you
Currently, $y = f(x)$

So we can say that $y + \Delta y = f(x+ \Delta x)$

We can then re-write this as: $\Delta y = f(x+\Delta x) - y$

And we know that $y = f(x)$, so we can say:

$\Delta y = f(x+\Delta x) - f(x)$

We know that $f(x) = 4 \sqrt{x}$

So:

$\Delta y = 4 \sqrt{x + \Delta x} - 4 \sqrt{x}$

For the second part, just differentiate it and then take it from there.

3. for the first one use the formula;
= f(x+delta(x))-f(x)
and for the other
dy=f'(x)dx