Differentiation HELP! (1 Viewer)

[lolzlolz]

can anyone help with question 8 please

 

[lolzlolz]

f'(x) = ln4 . 4^(x+1)
sub in x = 4 to find slope
f'(x) = ln4 . 4
sub in to y - y1 = m(x-x1) for x=0,y=4
y-4=4.ln4(x-0)
y=4xln4+4

I think that should be it

what is the last line?

 

[mmmmmmmmaaaaaaa]

what is the last line?

I plugged wrong value in
I will work it out again

 

[lolzlolz]

I plugged wrong value in
I will work it out again

because it says the answer is

xln4-y+4 = 0

idk if that's right

 

[mmmmmmmmaaaaaaa]

I plugged wrong value in
I will work it out again

the last line is just equating for when m = 4ln4 and when x=0,y=4
y-y1=m(x-x1)
y-4=4ln4(x-0)
y=4xln4+4
0=4xln4+4 -y