Answer with explanation:
Let us assume that the 2 functions are:
1) f(x)
2) g(x)
Now by definition of concave function we have the first derivative of the function should be strictly decreasing thus for the above 2 function we conclude that

Now the sum of the 2 functions is shown below

Diffrentiating both sides with respect to 'x' we get

Since each term in the right of the above equation is negative thus we conclude that their sum is also negative thus

Thus the sum of the 2 functions is also a concave function.
Part 2)
The product of the 2 functions is shown below

Diffrentiating both sides with respect to 'x' we get

Now we can see the sign of the terms on the right hand side depend on the signs of the function's themselves hence we remain inconclusive about the sign of the product as a whole. Thus the product can be concave or convex.
k-4/3= 3
Mutiply both sides by 3 .
(3)(k-4/3)= (3)(3)
Cross out 3 and 3 , divide by 3 and then becomes k-4= 9
Move -4 to the other side
Sign changes from -4 to +4
k-4+4= 9+4
k= 13
Answer: k= 13
Length of blue cloth is 60 inches , length of gold cloth is 48 inches and length of white cloth is 72 inches.
<u>a.</u>
As, the length of all pieces are equal, so for getting the greatest possible length of the pieces, we need to find <u>GCF(greatest common factor) of 60, 48 and 72. </u>
First we will factor out all three numbers completely......

The common factors are: 2, 2 and 3
Thus the GCF 
So, the greatest possible length of the pieces without having any cloth left over will be 12 inches.
<u>b. </u>
For finding the number of pieces for each color cloth, we will just <u>divide the length of each cloth by 12</u>. So...
Number of pieces for blue cloth 
Number of pieces for gold cloth
and
Number of pieces for white cloth 
Answer:
no
Step-by-step explanation:
(f-g)(x) = 4x²-2x-12 which,evaluated at x=4, gives 64-8-12=44