Answer:
(23/2, 1/2)
Step-by-step explanation:
Let's solve this system through elimination by addition/subtraction:
Divide all three terms of the first equation by 3.  This results in the equivalent system
-2x - 2y = 33
 2x + 4y = -32
Combining like terms results in:
2y = 1, and so y = 1/2.
Let's use the first equation and y = 1/2 to find x:
-6x - 6(1/2) = 66
This becomes -6x - 3 = 66, or -6x = 69, or x = -69/6 , or x = 23/2 
The solution is thus (23/2, 1/2)
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Answer:
I think B and C are the only ones true
 
        
             
        
        
        
F(x) = -4x^7 +x^3 -x^2 +5
a) It is a degree 7 polynomial, so will have 7 zeros (some may be repeated).
b) has 3 sign changes, so 1 or 3 positive real zeros. If odd powers have their signs reversed, the signs are changed to +--+, so there are 2 sign changes. There will be 0 or 2 negative real zeros.
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There is actually 1 positive real zero and 0 negative real zeros. This means there are 3 conjugate pairs of complex zeros.
 
        
        
        
Answer:
The correct answer is - C. 24.1%
Step-by-step explanation:
Given:
mean μ = 65%
standard deviation δ = 7.1 %
solution:
Prob( X>70) = 1 - Prob(x<70)  
= P (x-μ/δ ≥ 70 -65/7.1)
= 1 - Prob( (70-65)/7.1) 
= 1 - Prob ( z < 0.7042553) 
= 0.24065 
the percentage of students scoring 70 or more in the exam
= 24.065*100
= 24.1%
 
        
             
        
        
        
F. 30 is the correct answer, for mean you just have to add all the ages together and divide by the number of customers