# Thread: i want yr sullotions in this questions plz?

1. ## i want yr sullotions in this questions plz?

hello all
i'm really happy caz i found a furums that will help me in my homework and this is also quaetions can help me plz/

thax 4 all agian.

2. Originally Posted by eman.kh
hello all
i'm really happy caz i found a furums that will help me in my homework and this is also quaetions can help me plz/

thax 4 all agian.
i suppose these are calculus questions...

for image003 the function $f(x) = 3 + 4x^3 - x^4$..

a)
$f'(x) = 12x^2 -4x^3$
at x=1, $f'(x)=8$, hence the equation of the tangent line at the point (1,6) is y-6 = 8(x-1) and the equation of the line perpendicular to it is $y-6=\frac{-1}{8}(x-1)$
b) solve for $f'(x) = 0$ and plug in the values of x in f(x) to find their corresponding ordinates..
c) on the interval [-1,2]
f(-1) = -2
f(2) = 19
and f(-1)f(2) = -38 < 0
so, by a corollary to the IVT, there is a c such that f(c) = 0.
indeed, $f(c) = 3 + 4c^3 - c^4 = 0$, solving for c, we have (using a calculating device) -.8519, and 4.0453
Ü