11) -x + y = -1 ; 2x - y = 0
y = -1 + x ; 2x - (-1+x) = 0 ⇒ 2x + 1 - x = 0 ⇒x = -1 
y = -1 + (-1) ⇒ y = -2
12) -2x + y = -20 ; 2x + y = 48
y = -20 + 2x ; 2x + (-20 + 2x) = 48 ⇒ 2x -20 + 2x = 48 ⇒ 4x = 48 + 20
                      4x = 68 ⇒ x = 68/4 ⇒ x = 17
y = -20 + 2(17) ⇒ y = -20 + 34 ⇒ y = 14
13) 3x -y = -2 ; -2x + y = 3
y = 3 + 2x ; 3x - (3 + 2x) = -2 ⇒ 3x - 3 - 2x = -2 ⇒ x = -2 + 3 ⇒ x = 1
y = 3 + 2(1) ⇒ y = 3 + 2 ⇒ y = 5
14) x - y = 4 ; x - 2y = 10
x = 4 + y ; (4 + y) - 2y = 10 ⇒ 4 + y - 2y = 10 ⇒ 4 - y = 10 
                  ⇒ -y = 10 - 4 ⇒ -y = 6 ⇒  y = -6
x = 4 + (-6) ⇒ x = 4 - 6 ⇒ x = -2
15) x + 2y = 5 ; 3x + 2y = 17
x = 5 - 2y ; 3(5-2y) + 2y = 17 ⇒ 15 - 6y + 2y = 17 ⇒ -4y = 17 - 15
               ⇒ -4y = 2 ⇒ y = -2/4 ⇒ y = -1/2
x = 5 - 2(-1/2) ⇒ x = 5 + 2/2 ⇒ x = 5 + 1 ⇒ x = 6 
        
                    
             
        
        
        
Answer:
The answer to your questions is below
Step-by-step explanation:
4.-
In a 45°-45°-90° triangle, the length of the legs are "x" and the length of the hypotenuse is x
Then, in this problem, the length of the leg is 7 then the length of the hypotenuse will be 7
5.- In a 30°-60°-90° triangle, the length of the hypotenuse is 2x, the length of the longer leg is x and the length of the shorter leg is x.
 and the length of the shorter leg is x.
In this problem we have the length of the hypotenuse = 20 and find x.
                           2x = 20
                              x = 20/2
                              x = 10
           longer leg = x
6.- nonzero
7.- hypotenuse = 20 cm
      Find x
                          2x = 20
                            x = 20/2
                           x = 10
    Shoter leg = x = 10 cm
 
        
                    
             
        
        
        
Answer:
but what is the value of term 'n'
Step-by-step explanation:
n=3
2n-1
2×3-1
6-1
5 
Ans 
 
        
             
        
        
        
Answer:
80*
Step-by-step explanation: