Answer:
a)
.
b) 
Step-by-step explanation:
Given a function
, this function has the following gradient:
.
(a) find the gradient of f
We have that
. So


.
.

(b) find the directional derivative of f at (2, 4, 0) in the direction of v = i + 3j − k.
The directional derivate is the scalar product between the gradient at (2,4,0) and the unit vector of v.
We have that:

.

The vector is 
To use v as an unitary vector, we divide each component of v by the norm of v.

So

Now, we can calculate the scalar product that is the directional derivative.

Answer:
$19.26 or $19.
Step-by-step explanation:
Sold DVD for 50% more of the purchase price of $12, so:
12 + 50/100 * (12) = 12 + 6 = 18.
The customer will pay 7% tax on $18.
18 * (1.07) = $19.26
The normal body temperature : to = 37° C
An inequality is:
| t - to | ≤ 3
| t - 37 | ≤ 3
t - 37 ≤ 3 AND ( - t - 37 ) ≤ 3
t ≤ 3 +
37
- t + 37 ≤ 3
t ≤
40
- t ≤ 3 - 37
- t ≤ - 34 / *( - 1 )
t ≥ 34
Answer t <span>∈ [</span><span>
34</span><span>°C,</span><span>
40</span><span>° C ]</span>.
(y+3)(y^2-3y+9)
=y(y^2-3y+9)
+3(y^2-3y+9)
=(y^3-3y^2+9y)+(3y^2-9y+27)
=y^3-3y^2+9y+3y^2-9y+27
=y^3+27
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Add sides 6


Divide sides by 2


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The correct answer is (( B )) .
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