Answer:
1.) 17.15
2.)112
3.)99
I think these are right
Step-by-step explanation:
 
        
                    
             
        
        
        
Answer:
robert is 12 years old
Step-by-step explanation:
robert's age=x
40=3x+4
that's the equation
40=3x+4
=36=3x
x=12
 
        
             
        
        
        
Answer:
The square roots of 49·i in ascending order are;
1) -7·(cos(45°) + i·sin(45°)) 
2) 7·(cos(45°) + i·sin(45°)) 
Step-by-step explanation:
The square root of complex numbers 49·i is found as follows;
x + y·i = r·(cosθ + i·sinθ)
Where;
r = √(x² + y²)
θ = arctan(y/x)
Therefore;
49·i = 0 + 49·i
Therefore, we have;
r = √(0² + 49²) = 49
θ = arctan(49/0) → 90°
Therefore, we have;
49·i = 49·(cos(90°) + i·sin(90°)
By De Moivre's formula, we have;

Therefore;
√(49·i) = √(49·(cos(90°) + i·sin(90°)) = ± √49·(cos(90°/2) + i·sin(90°/2)) 
∴ √(49·i) = ± √49·(cos(90°/2) + i·sin(90°/2)) = ± 7·(cos(45°) + i·sin(45°)) 
√(49·i) = ± 7·(cos(45°) + i·sin(45°)) 
The square roots of 49·i in ascending order are;
√(49·i) = - 7·(cos(45°) + i·sin(45°))  and  7·(cos(45°) + i·sin(45°))