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[20x^2/4x^2y]+[4xy^2/4x^2y]-[8y^2/4x^2y]
[5/y]+[y]-[4y/x^2]
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.
Answer:
The answer is: y=2x−8
Step-by-step explanation:
Step 1: Add -8x to both sides.
8x−4y+−8x=32+−8x
−4y=−8x+32
Step 2: Divide both sides by -4.
−4y−4=−8x+32−4
y=2x−8
Answer:
124°
Step-by-step explanation:
cos X = (11²+7²-16²)/2(11)(7)
= (121+49-256)/154
= -86/154
= -0.5584
X = cos~¹ -0.5584 = 124°
The series 7 + 16 + 25 +34 +43 +52 + 61 is an illusration of arithmetic series
The sigma notation of the series is: 
<h3>How to write the series in sigma notation?</h3>
The series is given as:
7 + 16 + 25 +34 +43 +52 + 61
The above series is an arithmetic series, with the following parameters
- First term, a = 7
- Common difference, d = 9
- Number of terms, n = 7
Start by calculating the nth term using:
a(n) = a + (n - 1) * d
This gives
a(n) = 7 + (n - 1) * 9
Evaluate the product
a(n) = 7 - 9 + 9n
Evaluate the difference
a(n) = 9n - 2
So, the sigma notation is:

Read more about arithmetic series at:
brainly.com/question/6561461