21 is the answer.You distribute 6 into the parentheses and you substitute 3 for x so 6(3-1)+9= f(x)=18-6+9 you add all the like terms and the answer is 21
        
                    
             
        
        
        








I'm not the best at writing, but I can try. so here's an idea:you can have as your scenario something like "On a vase shaped like a rectangular prism is a flower. Knowing that the stem of the flower is the diagonal of the prism, the diagonal of the base is 18 and the sinus of the angle between the stem and the diagonal(of the base) is 4/5, find the stem's length and the height of the vase"
        
                    
             
        
        
        
Answer:415320
Step-by-step explanation:
 
        
                    
             
        
        
        
Answer:
 Center: (-5,10)
 Radius: 2
Step-by-step explanation:
 The equation of the circle in center-radius form is:
 
 Where the point (h,k)  is the center of the circle and "r" is the radius.
 Subtract 121 from both sides of the equation:
 
 Add 10x to both sides:
 
 Make two groups for variable "x" and variable "y":
 
 Complete the square:
 Add  inside the parentheses of "x".
 inside the parentheses of "x".
 Add   inside the parentheses of "y".
  inside the parentheses of "y".
 Add  and
 and  to the right side of the equation.
 to the right side of the equation.
 Then:
 
 Rewriting, you get that the equation of the circle in center-radius form is:
  
 You can observe that the radius of the circle is:
 
 And the center is:
 